Selected Appendixes: 2010

2010 Census of Population and Housing

Issued June 2012

Population and Housing Unit Counts

CPH-2-A

U.S. Department of Commerce

Economics and Statistics Administration

U.S. CENSUS BUREAU

census.gov

U.S. Department of Commerce

Rebecca M. Blank, 

Acting Secretary

Rebecca M. Blank, 

Deputy Secretary

Economics and Statistics Administration 

Vacant, 

Under Secretary 

for Economic Affairs

U.S. CENSUS BUREAU 

Robert M. Groves, 

Director

Selected Appendixes: 2010

Population and Housing Unit Counts

Issued June 2012

CPH-2-A
ECONOMICS

AND STATISTICS

ADMINISTRATION

Economics 

and Statistics

Administration

Vacant,

Under Secretary for 

Economic Affairs

U.S. CENSUS BUREAU

Robert M. Groves,

Director

Thomas L. Mesenbourg,

Deputy Director and 

Chief Operating Officer

Nancy A. Potok,

Associate Director

for Demographic Programs

Enrique J. Lamas,

Chief, Population Division

SUGGESTED CITATION

U.S. Census Bureau,

2010 Census of

Population and Housing,

Population and 

Housing Unit Counts,

CPH-2-A, Selected Appendixes

U.S. Government Printing Office,

Washington, DC,

2012
Contents iii

How to Use This Census Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-1

Appendixes

A Geographic Terms and Concepts . . . . . . . . . . . . . . . . . . . . . . . . A-1

B Definitions of Subject Characteristics . . . . . . . . . . . . . . . . . . . . . B-1

C Data Collection and Processing Procedures . . . . . . . . . . . . . . . . . C-1

D Questionnaire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1

E Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *

F Operational Overview and Accuracy of the Data . . . . . . . . . . . . . F-1

G Residence Rule and Residence Situations for the 2010 Census 

 of the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

H Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H-1

*Maps may be found in the Population and Housing Unit Counts, CPH-2 statistical 

reports, in print and on the Internet at <www.census.gov/prod/cen2010/>.

CONTENTS

How to Use This Census Report I-1

U.S. Census Bureau, 2010 Census

How to Use This Census Report

The appendixes contained in this volume supplement the 2010 Census, Population and Housing Unit 

Counts reports for the United States, states, the District of Columbia, and Puerto Rico. These reports provide 2010 Census and historical comparisons of the population and housing unit counts. They also provide 

area measurements and density. The user notes section of each report documents geographic changes 

over the past decade. This series is similar to the Census 2000 PHC-3 series.

Appendixes A through D, and F through H, described below, are in this report. Appendix E is found in the 

separate statistical reports of the CPH-2, Population and Housing Unit Counts, or on the Internet at 

<www.census.gov/prod/cen2010/>. 

Appendix A, Geographic Terms and Concepts. Provides definitions of the types of geographic areas 

and related information used in census products.

Appendix B, Definitions of Subject Characteristics. Contains definitions for the subject matter terms 

used in census products, including explanations of derived measures, limitations of the data, and comparability with previous censuses. The subjects are listed alphabetically. Population characteristics are 

defined first, followed by the definitions of the housing subjects.

Appendix C, Data Collection and Processing Procedures. Explains the 2010 Census mission and 

scope and provides thumbnail descriptions of 2010 Census operations.

Appendix D, Questionnaire. Presents a facsimile of the 2010 Census questionnaire used to collect the 

data in this report.

Appendix E, Maps. Contains maps depicting the geographic areas shown in this report.

Appendix F, Operational Overview and Accuracy of the Data. Provides information on confidentiality of the data, imputation of housing unit status and population counts, sources of errors in the data, and 

data editing.

Appendix G, Residence Rule and Residence Situations for the 2010 Census of the 

United States. Contains a description of the residence rule and residence situations used by Census 

Bureau staff to guide decisions on where people should be counted in the 2010 Census. This document is 

the basis for residence-related sections of questionnaires, collection instruments, field materials, and training materials.

Appendix H, Acknowledgments. Lists many of the U.S. Census Bureau staff who participated in report 

preparation.

Any changes to or explanatory information about the reports in this series that occur after they have gone 

to print are available at <www.census.gov/prod/cen2010/notes/errata.pdf>.

Geographic Terms and Concepts A-1

U.S. Census Bureau, 2010 Census

Appendix A.

Geographic Terms and Concepts

Alaska Native Regional Corporation (ANRC) (see American Indian, Alaska Native, 

and Native Hawaiian Area) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-5

Alaska Native Village (ANV) (see American Indian, Alaska Native, and Native Hawaiian Area). . . . . A-5

Alaska Native Village Statistical Area (ANVSA) (see American Indian, Alaska Native,

and Native Hawaiian Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8

American Indian, Alaska Native, and Native Hawaiian Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-5

American Indian Off-Reservation Trust Land (see American Indian, Alaska Native,

and Native Hawaiian Area) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-7

American Indian Reservation (see American Indian, Alaska Native,

and Native Hawaiian Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-6

American Indian Tribal Subdivision (see American Indian, Alaska Native,

and Native Hawaiian Area) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-6

American National Standards Institute (ANSI) Codes (see Codes for Geographic Entities). . . . . . . . . A-13

American Samoa (see Island Areas of the United States) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Area Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-9

Barrio (see Puerto Rico) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Barrio-Pueblo (see Puerto Rico). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-10

Block Group (BG). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-10

Borough (see County or Statistically Equivalent Entity; see County Subdivision; see Place) . . . . . . . A-16

Boundary Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-11

Census Area (see County or Statistically Equivalent Entity). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-16

Census Block (see Block). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-10

Census Bureau Codes (see Codes for Geographic Entities). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-14

Census County Division (CCD) (see County Subdivision) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-18

Census Designated Place (CDP) (see Place) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-21

Census Division (see also Census Region) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-12

Census Region (see also Census Division) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-12

Census Subarea (see County Subdivision). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-18

Census Tract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-12

Central Place (see Urban and Rural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

City (see Place). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-21

City and Borough (see County or Statistically Equivalent Entity; see Place). . . . . . . . . . . . . . . . . . . A-16

Codes for Geographic Entities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-13

Combined New England City and Town Area (see Core Based Statistical Area). . . . . . . . . . . . . . . . . A-15

Combined Statistical Area (CSA) (see Core Based Statistical Area) . . . . . . . . . . . . . . . . . . . . . . . . . . A-15

Commonwealth of the Northern Mariana Islands (see Island Areas of the United States) . . . . . . . . . A-20

Comparability (see Boundary Changes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-11

Comunidad (see Puerto Rico) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Congressional District (CD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-14

Consolidated City. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-14

Core Based Statistical Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-15

County or Statistically Equivalent Entity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-16

County Subdivision. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-17
A-2 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

Density (see Population and Housing Unit Density). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

District (see County or Statistically Equivalent Entity). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-16

Division (see Census Division) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-12

Extended Place (see Urban and Rural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

FIPS Class Codes (see Geographic Area Attributes). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-18

FIPS Codes (see Codes for Geographic Entities). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-13

Functional Status (see Geographic Area Attributes). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-19

Geographic Area Attributes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-18

Geographic Hierarchy (see Introduction—Geographic Presentation of Data) . . . . . . . . . . . . . . . . . . A-4

Geographic Names Information System (GNIS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Geographic Names Information System Identifier (GNIS ID) (see Codes for

Geographic Entities). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Geographic Presentation (see Introduction—Geographic Presentation of Data) . . . . . . . . . . . . . . . . A-4

Guam (see Island Areas of the United States) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Hawaiian Home Land (HHL) (see American Indian, Alaska Native, and Native Hawaiian Area). . . . . A-7

Hierarchical Presentation (see Introduction—Geographic Presentation of Data) . . . . . . . . . . . . . . . . A-4

Incorporated Place (see Place; see County Subdivision) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-21

Independent City (see County or Statistically Equivalent Entity; see Place) . . . . . . . . . . . . . . . . . . . A-16

Independent Place (see County Subdivision; see Place). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-17

Internal Point (see Geographic Area Attributes). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-19

Introduction—Geographic Presentation of Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

Inventory Presentation (see Introduction—Geographic Presentation of Data) . . . . . . . . . . . . . . . . . A-4

Island (see County or Statistically Equivalent Entity) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-16

Island Areas of the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Joint-Use Areas (see American Indian Area, Alaska Native Area, and Hawaiian Home Land) . . . . . . . A-7

Land Area (see Area Measurement) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-9

Legal/Statistical Area Description (LSAD) (see Geographic Area Attributes). . . . . . . . . . . . . . . . . . . A-19

MAF/TIGER (Master Address File/Topologically Integrated Geographic Encoding and 

Referencing) Database. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Metropolitan Division (see Core Based Statistical Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-15

Metropolitan Statistical Area (see Core Based Statistical Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-15

Micropolitan Statistical Area (see Core Based Statistical Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-15

Minor Civil Division (MCD) (see County Subdivision) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-17

Municipality (see County or Statistically Equivalent Entity; see Place) . . . . . . . . . . . . . . . . . . . . . . . A-16

Municipio (see Puerto Rico; see County or Statistically Equivalent Entity) . . . . . . . . . . . . . . . . . . . . A-22

Names of Geographic Entities (see Geographic Area Attributes). . . . . . . . . . . . . . . . . . . . . . . . . . . A-19

National Standard Feature Identifier (see Codes for Geographic Entities; see Geographic

Names Information System [GNIS ID]). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-13

New England City and Town Area (NECTA) (see Core Based Statistical Area). . . . . . . . . . . . . . . . . . . A-16

New England City and Town Area Division (see Core Based Statistical Area). . . . . . . . . . . . . . . . . . A-16

Northern Mariana Islands (see Island Areas of the United States). . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Off-Reservation Trust Land (see American Indian, Alaska Native, and Native Hawaiian Area). . . . . . A-7

Oklahoma Tribal Statistical Area (OTSA) (see American Indian, Alaska Native, and 

Native Hawaiian Area) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8

Oklahoma Tribal Statistical Area (OTSA) Joint-Use Area (see American Indian, Alaska Native, 

and Native Hawaiian Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8

Outlying Areas (see Island Areas of the United States). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Parish (see County or Statistically Equivalent Entity) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-16
Geographic Terms and Concepts A-3

U.S. Census Bureau, 2010 Census

Place. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-21

Place Within Consolidated City (see Place) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-21

Population and Housing Unit Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Principal City (see Core Based Statistical Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-16

Public Use Microdata Area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Puerto Rico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Region (see Census Region) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-12

Rural (see Urban and Rural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

School District (Elementary, Secondary, and Unified). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-23

State or Statistically Equivalent Entity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-23

State Designated American Indian Statistical Area (SDAISA) (see American Indian,

Alaska Native, and Native Hawaiian Area) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-5

State Designated Tribal Statistical Area (SDTSA) (see American Indian, Alaska Native,

and Native Hawaiian Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8 

State Legislative District (Upper and Lower Chambers). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-23

Subbarrio (see Puerto Rico) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Subminor Civil Division. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-13

Town (see County Subdivision; see Place) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-17

Township (see County Subdivision) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-17

Tract (see Census Tract). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-12

Tribal Block Group (see Block Group). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-24

Tribal Census Tract (see Census Tract). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-24

Tribal Designated Statistical Area (TDSA) (see American Indian, Alaska Native, 

and Native Hawaiian Area) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-9

Trust Land (see American Indian, Alaska Native, and Native Hawaiian Area) . . . . . . . . . . . . . . . . . . A-5

United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

U.S. Minor Outlying Islands (see Island Areas of the United States). . . . . . . . . . . . . . . . . . . . . . . . . A-20

U.S. Virgin Islands (see Island Areas of the United States). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Unorganized Territory (see County Subdivision). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-18

Urban (see Urban and Rural). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

Urban and Rural. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

Urban Cluster (UC) (see Urban and Rural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

Urban Growth Area (UGA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-26

Urbanized Area (UA) (see Urban and Rural) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

Village (see Place). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-21

Voting District. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-26

Water Area (see Area Measurement) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-9

ZIP Code (see ZIP Code Tabulation Area). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-26

ZIP Code Tabulation Area (ZCTA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-26

Zona Urbana (see Puerto Rico) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

INTRODUCTION

This document provides definitions of geographic terms and concepts as well as a description of the 

different methods used to present information for geographic entities in U.S. Census Bureau data products. 

This document contains definitions for all geographic area terms and concepts recognized by the Census 

Bureau and that may appear in any Census Bureau product presenting demographic and housing data 

(geographic terms and concepts unique to the economic census and other specialized surveys and 

censuses are not included in this document). The inclusion of a particular term or concept in this 
A-4 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

document does not imply that data for that geographic entity or attribute appear in each data 

product. For instance, data for tribal census tracts and tribal block groups will appear only in products 

providing data according to the American Indian Nation-based geographic hierarchy (see Figure A-2). As 

another example, because urban areas are defined on the basis of decennial census population counts, 

data for urban areas do not appear in initial decennial census data products. In addition, the description of 

both the hierarchical and inventory approaches to presenting data for geographic entities does not imply 

that both formats are used in each data product.

GEOGRAPHIC PRESENTATION OF DATA

In Census Bureau data products, geographic entities usually are presented in a hierarchical arrangement or 

as an inventory listing.

Hierarchical Presentation

A hierarchical geographic presentation shows the geographic entities in a superior/subordinate 

structure. This structure is derived from the legal, administrative, or areal relationships of the entities. 

The hierarchical structure is depicted in report tables by means of indentation. For computer-readable 

media, the hierarchy is shown in the descriptive name applied to a summary level, with the hierarchy 

in order separated by hyphens. An example of hierarchical presentation is the census geographic 

hierarchy consisting of census block, within block group, within census tract, within place, within county 

subdivision, within county, within state. Graphically, this is shown as:

State

 County

 County subdivision

 Place (or part)

 Census tract (or part)

 Block group (or part)

 Block

Figure A-1, which is a diagram of the geographic hierarchy, presents this information as a series of nesting 

relationships. For example, a line joining the lower-level entity place and the higher-level entity state 

means that a place cannot cross a state boundary; a line linking census tract and county means that a 

census tract cannot cross a county line; and so forth. There is no implied hierarchy between different line 

tracks; for example, census tract nests within county, but it may cross a county subdivision boundary even 

though county subdivision also nests within county.

Inventory Presentation

An inventory presentation of geographic entities is one in which all entities of the same type are shown in 

alphabetical, code, or geographic sequence, without reference to their hierarchical relationships. Generally, 

an inventory presentation shows totals for entities that may be split in a hierarchical presentation, such as 

place, census tract, or block group. An example of a series of inventory presentations is state, followed by 

all the counties in that state, followed by all the places in that state. Graphically, this is shown as:

State

County A

County B

County C

Place X

Place Y

Place Z
Geographic Terms and Concepts A-5

U.S. Census Bureau, 2010 Census

Nation-Based Hierarchies

Exceptions to the standard hierarchical presentation occur for entities that do not necessarily nest within 

states, most notably American Indian, Alaska Native, and Native Hawaiian areas and core based statistical 

areas.

American Indian, Alaska Native, and Native Hawaiian Area (AIANNHA) Hierarchy

Because federally recognized American Indian areas can cross state lines, a separate American Indian, 

Alaska Native, and Native Hawaiian area (AIANNHA) hierarchy exists for these areas. For instance, the 

following American Indian entities can cross state lines: federally recognized American Indian reservations 

and/or off-reservation trust lands, tribal subdivisions, tribal designated statistical areas, tribal census 

tracts, and tribal block groups. National summary data for American Indian reservations or statistical areas 

may be presented as an alphabetical listing of names followed by the state portions of each area. Also, a 

tribal census tract or tribal block group may be located in more than one state or county. Data for tribal 

census tracts and tribal block groups are presented only in Census Bureau products utilizing the AIANNHA 

hierarchy and are not present in products utilizing the standard census geographic hierarchy.

The diagram in Figure A-2 shows geographic relationships among geographic entities in the AIANNHA 

hierarchy. It does not show the geographic levels county, county subdivision, and place, among others, 

because AIANNHAs do not necessarily nest within them.

DEFINITIONS OF GEOGRAPHIC ENTITIES, TERMS, AND CONCEPTS

The definitions below are for geographic entities and concepts that the Census Bureau includes in its 

standard data products. Not all entities, terms, and concepts are shown in any one data product.

AMERICAN INDIAN, ALASKA NATIVE, AND NATIVE HAWAIIAN AREA

There are both legal and statistical American Indian, Alaska Native, and Native Hawaiian areas (AIANNHAs) 

for which the Census Bureau provides data. The legal entities consist of federally recognized American 

Indian reservations and off-reservation trust land areas, the tribal subdivisions that can divide these 

entities, state-recognized American Indian reservations, Alaska Native regional corporations, and Hawaiian 

home lands. The statistical entities are Alaska Native village statistical areas, Oklahoma tribal statistical 

areas, tribal designated statistical areas, and state designated tribal statistical areas. Statistical tribal 

subdivisions can exist within Oklahoma tribal statistical areas. In all cases, these areas are mutually 

exclusive in that no AIANNHA can overlap another tribal entity, except for tribal subdivisions, which by 

definition subdivide some American Indian entities, and Alaska Native village statistical areas, which exist 

within Alaska Native regional corporations. In cases where more than one tribe claims jurisdiction over an 

area, the Census Bureau creates a joint-use area as a separate entity to define this area of dual claims. The 

following provides more detail about each of the various AIANNHAs.

Legal Entities

Alaska Native regional corporations (ANRCs) were created pursuant to the Alaska Native Claims Settlement 

Act (ANCSA) (Pub. L. 92-203, 85 Stat. 688 [1971]; 43 U.S.C. 1602 et seq. [2000]), enacted in 1971 as a 

‘‘Regional Corporation’’ and organized under the laws of the state of Alaska to conduct both the for-profit 

and non-profit affairs of Alaska Natives within a defined region of Alaska. For the Census Bureau, ANRCs 

are considered legal geographic entities. Twelve ANRCs cover the entire state of Alaska except for the 

area within the Annette Island Reserve (a federally recognized American Indian reservation under the 

governmental authority of the Metlakatla Indian Community). A thirteenth ANRC represents Alaska Natives 

who do not live in Alaska and do not identify with any of the twelve corporations. The Census Bureau does 

not provide data for this thirteenth ANRC because it has no defined geographic extent and thus, it does 

not appear in the TIGER/Line® shapefiles. The Census Bureau offers representatives of the 12 nonprofit 

ANRCs in Alaska the opportunity to review and update the ANRC boundaries before each decennial census. 
A-6 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

Each ANRC is assigned a five-digit numeric Federal Information Processing Series (FIPS) code and an eightdigit National Standard (ANSI) code.

American Indian reservations—Federal (federal AIRs) are areas that have been set aside by the United 

States for the use of tribes, the exterior boundaries of which are more particularly defined in the final 

tribal treaties, agreements, executive orders, federal statutes, secretarial orders, or judicial determinations. 

The Bureau of Indian Affairs maintains a list of all federally recognized tribal governments and makes 

final determination of the inventory of federal AIRs. The Census Bureau recognizes federal reservations 

(and associated off-reservation trust lands) as territory over which American Indian tribes have primary 

governmental authority. American Indian reservations can be legally described as colonies, communities, 

Indian colonies, Indian communities, Indian rancherias, Indian reservations, Indian villages, pueblos, 

rancherias, ranches, reservations, reserves, settlements, or villages. The Census Bureau contacts 

representatives of American Indian tribal governments to identify the boundaries for federal reservations 

through its annual Boundary and Annexation Survey. Federal reservations may cross state and all other 

area boundaries.

Each federal AIR is assigned a four-digit census code ranging from 0001 through 4799 in alphabetical order 

of AIR names nationwide. This nation-based census code is the primary unique identifier for the AIR. Each 

federal AIR also is assigned a five-digit Federal Information Processing Series (FIPS) code and an eight-digit 

National Standard (ANSI) code. Because FIPS codes are assigned in alphabetical sequence within each state, 

the FIPS code will be different in each state for reservations that include territory in more than one state.

American Indian reservations—State (state AIRs) are reservations established by some state governments 

for tribes recognized by the state. A governor-appointed state liaison provides the names and boundaries 

for state-recognized American Indian reservations to the Census Bureau. State reservations must be 

defined within a single state but may cross county and other types of boundaries. Each state AIR is 

assigned a four-digit census code ranging from 9000 through 9499. Each state AIR also is assigned a fivedigit Federal Information Processing Series (FIPS) code and an eight-digit National Standard (ANSI) code. 

To further identify and differentiate state-recognized American Indian areas from those that are federally 

recognized, the text “(state)” is appended to the AIR name.

American Indian tribal subdivisions, described as additions, administrative areas, areas, chapters, county 

districts, communities, districts, or segments, are legal administrative subdivisions of federally recognized 

American Indian reservations and off-reservation trust lands or are statistical subdivisions of Oklahoma 

tribal statistical areas (OTSAs). These entities are internal units of self-government or administration 

that serve social, cultural, and/or economic purposes for the American Indians on the reservations, offreservation trust lands, or OTSAs. The Census Bureau obtains the boundary and name information for 

tribal subdivisions from tribal governments. Each American Indian tribal subdivision is assigned a threedigit census code that is alphabetically in order and unique within each American Indian area, a five-digit 

Federal Information Processing Series (FIPS) code assigned alphabetically within state, and an eight-digit 

National Standard (ANSI) code. Because FIPS codes are assigned in alphabetical sequence within each state, 

the FIPS code will be different in each state for tribal subdivisions that include territory in more than one 

state. All the summary levels that include tribal subdivisions in the presentation hierarchy will only have 

records for the 24 American Indian areas and two OTSAs that actually have tribal subdivisions. The list of 

areas and four-digit census codes is:
Geographic Terms and Concepts A-7

U.S. Census Bureau, 2010 Census

Code American Indian area

0335 Bois Forte Reservation, MN

0605 Cheyenne River Reservation and Off-Reservation Trust Land, SD

0855 Crow Creek Reservation, SD

0990 Eastern Cherokee Reservation, NC

1110 Flathead Reservation, MT

1150 Fort Belknap Reservation and Off-Reservation Trust Land, MT

1160 Fort Berthold Reservation, ND

1250 Fort Peck Indian Reservation and Off-Reservation Trust Land, MT

1310 Gila River Indian Reservation, AZ

1505 Hopi Reservation and Off-Reservation Trust Land, AZ

1830 Lac Vieux Desert Reservation, MI

1860 Lake Traverse Reservation and Off-Reservation Trust Land, ND-SD

2175 Menominee Reservation, WI

2430 Navajo Nation Reservation and Off-Reservation Trust Land, AZ-NM-UT

2490 Northern Cheyenne Indian Reservation and Off-Reservation Trust Land, MT

2810 Pine Ridge Reservation, SD-NE

3100 Red Lake Reservation, MN

3235 Rosebud Indian Reservation and Off-Reservation Trust Land, SD

3340 Salt River Reservation, AZ

3680 Shakopee Mdewakanton Sioux Community, MN

3935 Spirit Lake Reservation, ND

3970 Standing Rock Reservation, SD-ND

4200 Tohono O’odham Nation Reservation and Off-Reservation Trust Land, AZ

4290 Tulalip Reservation and Off-Reservation Trust Land, WA

5550 Cherokee OTSA, OK

5590 Choctaw OTSA, OK

Hawaiian home lands (HHLs) are areas held in trust for Native Hawaiians by the state of Hawaii, pursuant 

to the Hawaiian Homes Commission Act of 1920, as amended. The Census Bureau obtains the names 

and boundaries for HHLs from state officials. The names of the home lands are based on the traditional 

ahupua‘a names of the Crown and government lands of the Kingdom of Hawaii from which the lands were 

designated or from the local name for an area. Being lands held in trust, HHLs are treated as equivalent to 

off-reservation trust land areas with the American Indian Trust Land/Hawaiian Home Land Indicator coded 

as “T.” Each HHL is assigned a national four-digit census code ranging from 5000 through 5499 based on 

the alphabetical sequence of each HHL name, a five-digit Federal Information Processing Series (FIPS) code 

in alphabetical order within the state of Hawaii, and an eight-digit National Standard (ANSI) code.

Joint-use areas, as applied to any American Indian area by the Census Bureau, means an area that is 

administered jointly and/or claimed by two or more American Indian tribes. The Census Bureau designates 

legal joint-use areas as unique geographic entities equivalent to a reservation for the purpose of 

presenting statistical data. Each is assigned a national four-digit census code ranging from 4800 through 

4999 based on the alphabetical sequence of each joint-use area name, a five-digit Federal Information 

Processing Series (FIPS) code in alphabetical order within state, and an eight-digit National Standard (ANSI) 

code. No joint-use areas exist in multiple states.

Off-reservation trust lands are areas for which the United States holds title in trust for the benefit of a 

tribe (tribal trust land) or for an individual American Indian (individual trust land). Trust lands can be 

alienated or encumbered only by the owner with the approval of the Secretary of the Interior or his/her 

authorized representative. Trust lands may be located on or off a reservation; however, the Census Bureau 

tabulates data only for off-reservation trust lands with the off-reservation trust lands always associated 

with a specific federally recognized reservation and/or tribal government. As for federally recognized 

reservations, the Census Bureau obtains the boundaries of off-reservation trust lands from American Indian 
A-8 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

tribal governments through its annual Boundary and Annexation Survey. The Census Bureau recognizes 

and tabulates data for reservations and off-reservation trust lands because American Indian tribes have 

primary governmental authority over these lands. The Census Bureau does not identify fee land (or land in 

fee simple status) or restricted fee lands as specific geographic areas.

Off-reservation trust lands are assigned a four-digit census code, a five-digit Federal Information 

Processing Series (FIPS) code, and an eight-digit National Standard (ANSI) code that is the same as that 

for the reservation with which they are associated. Trust lands associated with tribes that do not have a 

reservation are assigned unique codes. The census code is assigned by tribal name within the range 0001 

through 4799, interspersed alphabetically among the reservation names. Because FIPS codes are assigned 

in alphabetical sequence within each state, the FIPS code will be different in each state for off-reservation 

trust lands that include territory in more than one state. In decennial census data tabulations, the 

American Indian Trust Land/Hawaiian Home Land Indicator uniquely identifies off-reservation trust lands, 

as well as reservation or statistical area only portions, Hawaiian home lands, and records that consist of 

the combination of reservation and off-reservation trust land territory.

Statistical Entities

Alaska Native village statistical areas (ANVSAs) represent the more densely settled portion of Alaska 

Native villages (ANVs). The ANVs constitute associations, bands, clans, communities, groups, tribes, or 

villages recognized pursuant to the Alaska Native Claims Settlement Act of 1971 (Public Law 92-203). 

Because ANVs do not have boundaries that are easy to locate, the Census Bureau does not delimit ANVs. 

Instead, the Census Bureau presents statistical data for ANVSAs that represent the settled portion of 

ANVs. In addition, each ANVSA should include only an area where Alaska Natives, especially members of 

the defining ANV, represent a substantial proportion of the population during at least one season of the 

year. ANVSAs are delineated or reviewed by officials of the ANV or, if no ANV official chose to participate 

in the delineation process, officials of the Alaska Native Regional Corporation (ANRC) in which the ANV is 

located. An ANVSA may not overlap the boundary of another ANVSA or an American Indian reservation. 

Each ANVSA is alphabetically assigned a national four-digit census code ranging from 6000 through 7999, 

an alphabetically assigned state-based five-digit Federal Information Processing Series (FIPS) code, and an 

eight-digit National Standard (ANSI) code.

Oklahoma tribal statistical areas (OTSAs) are statistical entities identified and delineated by the Census 

Bureau in consultation with federally recognized American Indian tribes that had a former reservation 

in Oklahoma. The boundary of an OTSA will be that of the former reservation in Oklahoma, except 

where modified by agreements with neighboring tribes for statistical data presentation purposes. Each 

OTSA is alphabetically assigned a national four-digit census code ranging from 5500 through 5899, an 

alphabetically assigned state-based five-digit Federal Information Processing Series (FIPS) code, and an 

eight-digit National Standard (ANSI) code. Tribal subdivisions are allowed within OTSAs and exist for the 

2010 Census in the Cherokee and Choctaw OTSAs.

Oklahoma tribal statistical area (OTSA) Joint-Use Areas, as applied to OTSAs by the Census Bureau, means 

an area that is administered jointly and/or claimed by two or more American Indian tribes that have a 

delineated OTSA. The Census Bureau designates statistical joint-use areas as unique geographic entities 

for the purpose of presenting statistical data. Only Oklahoma tribal statistical areas have statistical jointuse areas. Each Oklahoma tribal joint-use area is alphabetically assigned a national four-digit census code 

ranging from 5900 through 5999, an alphabetically assigned state-based five-digit Federal Information 

Processing Series (FIPS) code, and an eight-digit National Standard (ANSI) code.

State designated tribal statistical areas (SDTSAs—referred to as State Designated American Indian 

Statistical Areas for Census 2000) are statistical entities for state-recognized American Indian tribes 

that do not have a state-recognized land base (reservation). SDTSAs are identified and delineated for 

the Census Bureau by a state liaison identified by the governor’s office in each state. SDTSAs generally 

encompass a compact and contiguous area that contains a concentration of people who identify with a 
Geographic Terms and Concepts A-9

U.S. Census Bureau, 2010 Census

state-recognized American Indian tribe and in which there is structured or organized tribal activity. An 

SDTSA may not be located in more than one state and it may not include area within any other American 

Indian, Alaska Native, or Native Hawaiian area. Each SDTSA is alphabetically assigned a four-digit 

census code ranging from 9500 through 9998, an alphabetically assigned state-based five-digit Federal 

Information Processing Series (FIPS) code, and an eight-digit National Standard (ANSI) code.

Tribal designated statistical areas (TDSAs) are statistical entities identified and delineated for the Census 

Bureau by federally recognized American Indian tribes that do not currently have a federally recognized 

land base (reservation or off-reservation trust land). A TDSA generally encompasses a compact and 

contiguous area that contains a concentration of individuals who identify with a federally recognized 

American Indian tribe and in which there is structured or organized tribal activity. A TDSA may be 

located in more than one state (although none do for 2010), but it may not include area within any other 

American Indian, Alaska Native, or Native Hawaiian area. Each TDSA is alphabetically assigned a four-digit 

census code ranging from 8000 through 8999, an alphabetically assigned state-based five-digit Federal 

Information Processing Series (FIPS) code, and an eight-digit National Standard (ANSI) code.

American Indian, Alaska Native, and Native Hawaiian Area (AIANNHA) Codes—AIANNHAs are 

represented in Census Bureau products using a national four-character numeric census code field and a 

single alphabetic character American Indian trust land/Hawaiian home land indicator field. The census 

codes are assigned in alphabetical order in assigned ranges by AIANNHA type nationwide, except that 

joint-use areas appear at the end of the code range. Off-reservation trust lands are assigned the same code 

as the reservation with which they are associated. Trust lands associated with tribes that do not have a 

reservation are assigned codes based on tribal name. Federal Information Processing Series (FIPS) codes for 

all AIANNHAs range from 00001 through 89999, without differentiation among the many types of areas. 

The type of AIANNHA can be identified either by the census code or by the FIPS class code. The range 

of census codes allocated to each AIANNHA and the valid FIPS class code(s) associated with each are as 

follows: 

AIANNHA type Census

code range

Valid FIPS

class code(s)*

Federal American Indian reservation (AIR)/off-reservation

trust land. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0001 to 4799 D1, D2, D3, D5, D8

Joint-use federal AIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4800 to 4999 D0

Hawaiian home land. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5000 to 5499 F1

Oklahoma tribal statistical area (OTSA). . . . . . . . . . . . . . . . . . . . . 5500 to 5899 D6

Joint-use OTSA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5900 to 5999 D0

Alaska Native village statistical area (ANVSA). . . . . . . . . . . . . . . . 6000 to 7999 E1

Tribal designated statistical area (TDSA). . . . . . . . . . . . . . . . . . . . 8000 to 8999 D6

State AIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9000 to 9499 D4

State designated tribal statistical area (SDTSA). . . . . . . . . . . . . . . 9500 to 9998 D9

AIANNHA type American Indian, Alaska Native, Native 

Hawaiian area indicator

Hawaiian home land. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T

M

R

T 

American Indian reservation including associated 

 off-reservation trust land. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

American Indian reservation or statistical entity only. . . . . . . . . . 

Off-reservation trust land only. . . . . . . . . . . . . . . . . . . . . . . . . . . 

* Refer to the Data Dictionary for specific value descriptions.

AREA MEASUREMENT

Area measurement data provide the size, in square units (metric and nonmetric) of geographic entities for 

which the Census Bureau tabulates and disseminates data. Area is calculated from the specific boundary 
A-10 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

recorded for each entity in the Census Bureau’s geographic database (see “MAF/TIGER Database”). The 

Census Bureau provides area measurement data for both land area and water area. The water area 

figures include inland, coastal, Great Lakes, and territorial sea water. Inland water consists of any lake, 

reservoir, pond, or similar body of water that is recorded in the Census Bureau’s geographic database. It 

also includes any river, creek, canal, stream, or similar feature that is recorded in that database as a twodimensional feature (rather than as a single line). The portions of the oceans and related large embayments 

(such as Chesapeake Bay and Puget Sound), the Gulf of Mexico, and the Caribbean Sea that belong to the 

United States and its territories are classified as coastal and territorial waters; the Great Lakes are treated 

as a separate water entity. Rivers and bays that empty into these bodies of water are treated as inland 

water from the point beyond which they are narrower than 1 nautical mile across. Identification of land 

and inland, coastal, territorial, and Great Lakes waters is for data presentation purposes only and does not 

necessarily reflect their legal definitions.

Land and water area measurements may disagree with the information displayed on Census Bureau 

maps and in the MAF/TIGER database because, for area measurement purposes, hydrologic features 

identified as intermittent water, glacier, or swamp are reported as land area. The water area measurement 

reported for some geographic entities includes water that is not included in any lower-level geographic 

entity. Therefore, because water is contained only in a higher-level geographic entity, summing the water 

measurements for all the component lower-level geographic entities will not yield the water area of that 

higher-level entity. This occurs, for example, where water is associated with a county but is not within 

the legal boundary of any county subdivision. The accuracy of any area measurement data is limited by 

the accuracy inherent in 1) the location and shape of the various boundary information in the MAF/TIGER 

database, 2) the identification, and classification of water bodies coupled with the location and shapes of 

the shorelines of water bodies in that database, and 3) rounding affecting the last digit in all operations 

that compute and/or sum the area measurements.

BLOCK

Blocks (Census Blocks) are statistical areas bounded by visible features, such as streets, roads, streams, 

and railroad tracks, and by nonvisible boundaries, such as selected property lines and city, township, 

school district, and county limits and short line-of-sight extensions of streets and roads. Generally, census 

blocks are small in area; for example, a block in a city bounded on all sides by streets. Census blocks in 

suburban and rural areas may be large, irregular, and bounded by a variety of features, such as roads, 

streams, and transmission lines. In remote areas, census blocks may encompass hundreds of square miles. 

Census blocks cover the entire territory of the United States, Puerto Rico, and the Island Areas. Census 

blocks nest within all other tabulated census geographic entities and are the basis for all tabulated data.

Census Block Numbers—Census blocks are numbered uniquely with a four-digit census block number 

from 0000 to 9999 within census tract, which nest within state and county. The first digit of the census 

block number identifies the block group. Block numbers beginning with a zero (in Block Group 0) are only 

associated with water-only areas.

BLOCK GROUP

Block Groups (BGs) are statistical divisions of census tracts, are generally defined to contain between 

600 and 3,000 people, and are used to present data and control block numbering. A block group consists 

of clusters of blocks within the same census tract that have the same first digit of their four-digit census 

block number. For example, blocks 3001, 3002, 3003, . . ., 3999 in census tract 1210.02 belong to BG 

3 in that census tract. Most BGs were delineated by local participants in the Census Bureau’s Participant 

Statistical Areas Program. The Census Bureau delineated BGs only where a local or tribal government 

declined to participate, and a regional organization or State Data Center was not available to participate. 

A BG usually covers a contiguous area. Each census tract contains at least one BG, and BGs are uniquely 

numbered within the census tract. Within the standard census geographic hierarchy, BGs never cross state, 

county, or census tract boundaries but may cross the boundaries of any other geographic entity. Tribal 
Geographic Terms and Concepts A-11

U.S. Census Bureau, 2010 Census

census tracts and tribal BGs are separate and unique geographic areas defined within federally recognized 

American Indian reservations and can cross state and county boundaries (see “Tribal Census Tract” and 

“Tribal Block Group”). The tribal census tracts and tribal block groups may be completely different from the 

census tracts and block groups defined by state and county.

Block Group Codes—BGs have a valid code range of 0 through 9. BGs beginning with a zero only contain 

water area and are generally in coastal and Great Lakes water and territorial seas, but also in larger inland 

water bodies. For the 2010 Census, a block group 0 for the water portion can be delineated in any census 

tract and not just those census tracts also defined to only include water area. This is a change from Census 

2000, when block groups coded 0 only existed in census tracts with a code of 0. To differentiate between 

county-based block groups and tribal block groups, the codes for tribal block groups use an alphabetic 

character (see “Tribal Block Group”).

BOUNDARY CHANGES

Many of the legal and statistical entities for which the Census Bureau tabulates decennial census data have 

had boundary changes between Census 2000 and the 2010 Census; that is, between January 1, 2000, and 

January 1, 2010. Boundary changes to legal entities result from:

1. Annexations to or detachments from legally established governmental units.

2. Mergers or consolidations of two or more governmental units.

3. Establishment of new governmental units.

4. Disincorporations or disorganizations of existing governmental units.

5. Changes in treaties or executive orders and governmental action placing additional lands in trust.

6. Decisions by federal, state, and local courts.

7. Redistricting for congressional districts and state legislative districts.

8. Ancillary changes to legal or statistical areas as a result of annexations and detachments; for example, 

reduction of territory for a census designated place as the result of an annexation by an adjacent 

incorporated place.

9. Changes to correct errors or more accurately place boundaries relative to visible features.

10. Changes to statistical areas as the result of concept or criteria changes.

All legal boundaries used for the 2010 Census are those reported to the Census Bureau to be in effect as 

of January 1, 2010. The statistical area boundaries also reflect a January 1, 2010, date for delineation. 

The legal boundaries are collected through various surveys and programs: the Boundary and Annexation 

Survey, Redistricting Data Program, and the School District Review Program. There is a Geographic Change 

User Note Indicator in data files that identifies entities for which there have been changes to boundaries or 

data attributes (for example, legal/statistical area description or code) between the two censuses.

Statistical entity boundaries generally are reviewed by local, state, or tribal governments and can have 

changes to adjust boundaries to visible features to better define the geographic area each encompasses or 

to account for shifts and changes in the population distribution within an area. Where statistical areas have 

a relationship to legal area boundaries, complementary updates occur; for example, removing territory 

from a census designated place if annexed to an incorporated place or contracting a tribal designated 

statistical area if the area is added to an American Indian reservation.

The historical counts shown for states, counties, county subdivisions, places, American Indian, Alaska 

Native, and Native Hawaiian areas, and other areas are not updated for boundary changes and thus, reflect 

the population and housing units in each entity as delineated at the time of each decennial census.
A-12 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

CENSUS DIVISION

Census Divisions are groupings of states and the District of Columbia that are subdivisions of the four 

census regions (see “Census Region”). There are nine census divisions, and each is identified by a singledigit census code. Puerto Rico and the Island Areas are not part of any census region or census division. 

For a list of all census regions, census divisions, and their constituent states, see Figure A-3.

CENSUS REGION

Census Regions are groupings of states and the District of Columbia that subdivide the United States 

for the presentation of census data. There are four census regions—Northeast, Midwest, South, and West. 

Each of the four census regions is divided into two or more census divisions (see “Census Division”). 

Each census region is identified by a single-digit census code. Puerto Rico and the Island Areas are not 

part of any census region or census division. For a list of all census regions, census divisions, and their 

constituent states, see Figure A-3.

CENSUS TRACT

Census Tracts are small, relatively permanent statistical subdivisions of a county or equivalent entity that 

are updated by local participants prior to each decennial census as part of the Census Bureau’s Participant 

Statistical Areas Program. The Census Bureau delineates census tracts in situations where no local 

participant existed or where state, local, or tribal governments declined to participate. The primary purpose 

of census tracts is to provide a stable set of geographic units for the presentation of statistical data. 

Census tracts generally have a population size between 1,200 and 8,000 people, with an optimum size of 

4,000 people. A census tract usually covers a contiguous area; however, the spatial size of census tracts 

varies widely depending on the density of settlement. Census tract boundaries are delineated with the 

intention of being maintained over a long time so that statistical comparisons can be made from census to 

census. Census tracts occasionally are split due to population growth or merged as a result of substantial 

population decline.

Census tract boundaries generally follow visible and identifiable features. They may follow nonvisible 

legal boundaries, such as minor civil division (MCD) or incorporated place boundaries in some states 

and situations, to allow for census-tract-to-governmental-unit relationships where the governmental 

boundaries tend to remain unchanged between censuses. State and county boundaries always are census 

tract boundaries in the standard census geographic hierarchy. Tribal census tracts are a unique geographic 

entity defined within federally recognized American Indian reservations and off-reservation trust lands and 

can cross state and county boundaries. Tribal census tracts may be completely different from the census 

tracts and block groups defined by state and county (see “Tribal Census Tract”).

Census Tract Codes and Numbers—Census tracts are identified by an up to four-digit integer number 

and may have an optional two-digit suffix; for example 1457.02 or 23. The census tract codes consist of 

six digits with an implied decimal between the fourth and fifth digit corresponding to the basic census 

tract number but with leading zeroes and trailing zeroes for census tracts without a suffix. The tract 

number examples above would have codes of 145702 and 002300, respectively.

Some ranges of census tract numbers in the 2010 Census are used to identify distinctive types of census 

tracts. The code range in the 9400s is used for those census tracts with a majority of population, housing, 

or land area associated with an American Indian area and matches the numbering used in Census 2000. 

The code range in the 9800s is new for 2010 and is used to specifically identify special land-use census 

tracts; that is, census tracts defined to encompass a large area with little or no residential population 

with special characteristics, such as large parks or employment areas. The range of census tracts in the 

9900s represents census tracts delineated specifically to cover large bodies of water. This is different from 

Census 2000 when water-only census tracts were assigned codes of all zeroes (000000); 000000 is no 

longer used as a census tract code for the 2010 Census.
Geographic Terms and Concepts A-13

U.S. Census Bureau, 2010 Census

The Census Bureau uses suffixes to help identify census tract changes for comparison purposes. Census 

tract suffixes may range from .01 to .98. As part of local review of existing census tracts before each 

census, some census tracts may have grown enough in population size to qualify as more than one census 

tract. When a census tract is split, the split parts usually retain the basic number but receive different 

suffixes. For example, if census tract 14 is split, the new tract numbers would be 14.01 and 14.02. In a 

few counties, local participants request major changes to, and renumbering of, the census tracts; however, 

this is generally discouraged. Changes to individual census tract boundaries usually do not result in 

census tract numbering changes. 

Tribal Census Tracts in American Indian Areas—The Census Bureau introduced the concept of tribal 

census tracts for the first time for Census 2000. Tribal census tracts for that census consisted of the 

standard county-based census tracts tabulated within American Indian areas, thus allowing for the tracts 

to ignore state and county boundaries for tabulation. The Census Bureau assigned the 9400 range of 

numbers to identify specific tribal census tracts; however, not all tribal census tracts used this numbering 

scheme. For the 2010 Census, tribal census tracts no longer are tied to or numbered in the same way as 

the county-based census tracts (see “Tribal Census Tract”).

CODES FOR GEOGRAPHIC ENTITIES

The Census Bureau and other federal agencies assign codes to geographic entities to facilitate the 

organization, presentation, and exchange of statistical data and other information. Geographic entity codes 

allow for the unambiguous identification of individual entities, generally within a specific, higher-level 

geographic entity (for example, county codes are assigned uniquely within each state). For geographic 

entities that have names (such as states, counties, places, county subdivisions, urban areas, and 

metropolitan and micropolitan statistical areas), codes generally are assigned alphabetically based on name.

Census Bureau data products contain several types of geographic entity codes: Federal Information 

Processing Series (FIPS), American National Standards Institute (ANSI), and Census Bureau codes.

Federal Information Processing Series (FIPS)—These are codes formerly known as Federal Information 

Processing Standards codes, until the National Institute of Standards and Technology (NIST) announced 

its decision in 2005 to remove geographic entity codes from its oversight. The Census Bureau continues 

to maintain and issue codes for geographic entities covered under FIPS oversight, albeit with a revised 

meaning for the FIPS acronym. Geographic entities covered under FIPS include states, counties, 

congressional districts, core based statistical areas, places, county subdivisions, subminor civil divisions, 

consolidated cities, and all types of American Indian, Alaska Native, and Native Hawaiian areas. FIPS codes 

are assigned alphabetically according to the name of the geographic entity and may change to maintain 

alphabetic sort when new entities are created or names change. FIPS codes for specific geographic 

entity types are usually unique within the next highest level of geographic entity with which a nesting 

relationship exists. For example, FIPS state, congressional district, and core based statistical area codes are 

unique within nation; FIPS county, place, county subdivision, and subminor civil division codes are unique 

within state. The codes for American Indian, Alaska Native, and Native Hawaiian areas also are unique 

within state; those areas in multiple states will have different codes for each state.

American National Standards Institute (ANSI)—With the removal of geographic entities from Federal 

Information Processing Standards oversight, the Census Bureau and other federal agencies have sought 

American National Standards Institute (ANSI) oversight authority for geographic entity codes. These codes 

are referred to as “National Standard” codes in some Census Bureau products. Geographic entities covered 

under ANSI include states, counties, congressional districts, core based statistical areas and related 

statistical areas, places, county subdivisions, consolidated cities, subminor civil divisions, and all types of 

American Indian, Alaska Native, and Native Hawaiian areas—Alaska Native regional corporations, Alaska 

Native village statistical areas, American Indian reservation and off-reservation trust lands, American 

Indian tribal subdivisions, Hawaiian home lands, Oklahoma tribal statistical areas, state designated tribal 

statistical areas, and tribal designated statistical areas.
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U.S. Census Bureau, 2010 Census

Relationship between FIPS and ANSI codes—Geographic entities for which NIST formerly provided Federal 

Information Processing Standards oversight will continue to be referred to as FIPS (Federal Information 

Processing Series) codes in some Census Bureau data products, despite the Census Bureau having sought 

ANSI oversight authority. These geographic entities include states, counties, congressional districts, and 

core based statistical areas and related statistical areas. The Census Bureau continues to maintain and 

issue codes for these entities following the same structure and without change to existing codes, except 

when necessary to maintain alphabetic sorting based on names of entities. The Census Bureau also 

continues to maintain and issue five-digit FIPS codes (formerly FIPS 55) for places, county subdivisions, 

consolidated cities, subminor civil divisions, Alaska Native Regional Corporations, and all types of 

American Indian, Alaska Native, and Native Hawaiian areas but is not seeking ANSI oversight authority 

for these entity codes. The U.S. Geological Survey has ANSI oversight authority for its Geographic Names 

Information System identifier (GNIS ID), which has been adopted as a National Standard (NS) code for 

states, counties, places, county subdivisions, subminor civil divisions, consolidated cities, Alaska Native 

Regional Corporations, and all types of American Indian, Alaska Native, and Native Hawaiian areas. The 

Census Bureau will include the GNIS ID for these entities in its data products, portrayed as an eight-digit 

character numeric code and identified as “ANSI.” NS codes (GNIS IDs) will not sort geographic entities in 

alphabetical order based on name or title, as is the case with FIPS codes.

Census Bureau codes—The Census Bureau assigns and issues codes for a number of geographic entities for 

which FIPS or ANSI codes are not available, and sometimes in addition to FIPS and ANSI codes. Geographic 

entities for which census codes are assigned and issued in Census Bureau data products include regions, 

divisions, census tracts, block groups, census blocks, urban areas, and all types of American Indian, 

Alaska Native, and Native Hawaiian areas. Some codes—voting district, state legislative district, and school 

district—use standards established by the states—or for school districts, the U.S. Department of Education.

CONGRESSIONAL DISTRICT

Congressional Districts are the 435 areas from which people are elected to the U.S. House of 

Representatives. After the apportionment of congressional seats among the states based on decennial 

census population counts, each state with multiple seats is responsible for establishing congressional 

districts for the purpose of electing representatives. Each congressional district is to be as equal in 

population to all other congressional districts in a state as practicable. For the District of Columbia, Puerto 

Rico, and each Island Area, a separate code is used to identify the entire areas of these state-equivalent 

entities as having a single nonvoting delegate.

Congressional District Codes—Congressional districts are identified by a two-character numeric Federal 

Information Processing Series (FIPS) code numbered uniquely within state. The District of Columbia, Puerto 

Rico, and the Island Areas have code 98 assigned identifying their nonvoting delegate status with respect 

to representation in Congress:

01 to 53—Congressional district codes

00—At large (single district for state)

98—Nonvoting delegate

CONSOLIDATED CITY

Consolidated City—A consolidated government is a unit of local government for which the functions of 

an incorporated place and its county or minor civil division (MCD) have merged. This action results in both 

the primary incorporated place and the county or MCD continuing to exist as legal entities, even though 

the county or MCD performs few or no governmental functions and has few or no elected officials. Where 

this occurs—and where one or more other incorporated places in the county or MCD continue to function 

as separate governments, even though they have been included in the consolidated government—

the primary incorporated place is referred to as a consolidated city. The Census Bureau classifies the 
Geographic Terms and Concepts A-15

U.S. Census Bureau, 2010 Census

separately incorporated places within the consolidated city as place entities and creates a separate place 

(balance) record for the portion of the consolidated city not within any other place. 

Consolidated City (Balance) Portions refer to the areas of a consolidated city not included in another 

separately incorporated place. For example, Butte-Silver Bow, MT, is a consolidated city (former Butte city 

and Silver Bow County) that includes the separately incorporated municipality of Walkerville city. The area 

of the consolidated city that is not in Walkerville city is assigned to Butte-Silver Bow (balance). The name 

always includes the “(balance)” identifier (see “Place”).

CORE BASED STATISTICAL AREAS AND RELATED STATISTICAL AREAS

Core Based Statistical Areas (CBSAs) consist of the county or counties or equivalent entities associated 

with at least one core (urbanized area or urban cluster) of at least 10,000 population, plus adjacent 

counties having a high degree of social and economic integration with the core as measured through 

commuting ties with the counties associated with the core. The general concept of a CBSA is that of a 

core area containing a substantial population nucleus, together with adjacent communities having a high 

degree of economic and social integration with that core. The term “core based statistical area” became 

effective in 2003 and refers collectively to metropolitan statistical areas and micropolitan statistical areas. 

The U.S. Office of Management and Budget (OMB) defines CBSAs to provide a nationally consistent set of 

geographic entities for the United States and Puerto Rico for use in tabulating and presenting statistical 

data. Current CBSAs are based on application of the 2000 standards (published in the Federal Register of 

December 27, 2000) with Census 2000 data. The first set of areas defined based on the 2000 standards 

were announced on June 6, 2003; subsequent updates have been made to the universe of CBSAs and 

related statistical areas. No CBSAs are defined in the Island Areas. Statistical areas related to CBSAs include 

metropolitan divisions, combined statistical areas (CSAs), New England city and town areas (NECTAs), 

NECTA divisions, and combined NECTAs.

Combined New England City and Town Areas (Combined NECTAs) consist of two or more adjacent 

New England city and town areas (NECTAs) that have substantial employment interchange. The NECTAs 

that combine to create a combined NECTA retain separate identities within the larger combined NECTA. 

Because combined NECTAs represent groupings of NECTAs, they should not be ranked or compared with 

individual NECTAs.

Combined Statistical Areas (CSAs) consist of two or more adjacent CBSAs that have substantial 

employment interchange. The CBSAs that combine to create a CSA retain separate identities within the 

larger CSA. Because CSAs represent groupings of metropolitan and/or micropolitan statistical areas, they 

should not be ranked or compared with individual metropolitan and micropolitan statistical areas.

Metropolitan Divisions are smaller groupings of counties or equivalent entities defined within a 

metropolitan statistical area containing a single core with a population of at least 2.5 million. Not all 

metropolitan statistical areas with urbanized areas of this size will contain metropolitan divisions. A 

metropolitan division consists of one or more main/secondary counties that represent an employment 

center or centers, plus adjacent counties associated with the main/secondary county or counties through 

commuting ties. Because metropolitan divisions represent subdivisions of larger metropolitan statistical 

areas, it is not appropriate to rank or compare metropolitan divisions with metropolitan and micropolitan 

statistical areas. It would be appropriate to rank and compare metropolitan divisions.

Metropolitan Statistical Areas are CBSAs associated with at least one urbanized area that has a 

population of at least 50,000. The metropolitan statistical area comprises the central county or counties or 

equivalent entities containing the core, plus adjacent outlying counties having a high degree of social and 

economic integration with the central county or counties as measured through commuting.

Micropolitan Statistical Areas are CBSAs associated with at least one urban cluster that has a 

population of at least 10,000 but less than 50,000. The micropolitan statistical area comprises the central 

county or counties or equivalent entities containing the core, plus adjacent outlying counties having a 
A-16 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

high degree of social and economic integration with the central county or counties as measured through 

commuting.

New England City and Town Areas (NECTAs) are an alternative set of geographic entities, similar in 

concept to the county-based CBSAs defined nationwide, that OMB defines in New England based on county 

subdivisions—usually cities and towns. NECTAs are defined using the same criteria as county-based CBSAs, 

and, similar to CBSAs, NECTAs are categorized as metropolitan or micropolitan.

New England City and Town Area (NECTA) Divisions are smaller groupings of cities and towns 

defined within a NECTA containing a single core with a population of at least 2.5 million. A NECTA division 

consists of a main city or town that represents an employment center, plus adjacent cities and towns 

associated with the main city or town through commuting ties. Each NECTA division must contain a total 

population of 100,000 or more. Because NECTA divisions represent subdivisions of larger NECTAs, it is 

not appropriate to rank or compare NECTA divisions with NECTAs. It would be appropriate to rank and 

compare NECTA divisions.

Principal Cities of a CBSA (or NECTA) include the largest incorporated place with a population of at 

least 10,000 in the CBSA, or if no incorporated place of at least 10,000 population is present in the CBSA, 

the largest incorporated place or census designated place (CDP) in the CBSA. Principal cities also include 

any additional incorporated place or CDP with a population of at least 250,000 or in which 100,000 or 

more persons work; any additional incorporated place or CDP with a population of at least 50,000 and 

in which the number of jobs meets or exceeds the number of employed residents; and any additional 

incorporated place or CDP with a population of at least 10,000 but less than 50,000 and at least one-third 

the population size of the largest place and in which the number of jobs meets or exceeds the number of 

employed residents. Note that there are some places designated as principal cities of NECTAs that are not 

principal cities of a CBSA. 

Core Based Statistical Area Codes—Metropolitan statistical areas, micropolitan statistical areas, 

NECTAs, metropolitan divisions, and NECTA divisions are identified using a five-digit numeric code that is 

assigned alphabetically based on title and is unique within the nation. The combined statistical area and 

combined NECTAs are identified using a three-digit numeric code, also assigned alphabetically based on 

title and unique within the nation. Codes, length, and ranges are:

CBSA entity Length Range*

Metropolitan statistical area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Five digits 10000–49999

Micropolitan statistical area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Five digits 10000–49999

Metropolitan division. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Five digits 10004–49994 

New England city and town area (NECTA). . . . . . . . . . . . . . . . . . . . Five digits 70000–79999

NECTA division. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Five digits 70004–79994

Combined statistical area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Three digits 100–599

Combined NECTA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Three digits 700–799

* Metropolitan divisions and NECTA divisions are distinguished from metropolitan and micropolitan statistical areas and NECTAs by 

codes that end in “4.” Metropolitan and micropolitan statistical areas and NECTAs cannot end in “4.”

COUNTY OR STATISTICALLY EQUIVALENT ENTITY

The primary legal divisions of most states are termed counties. In Louisiana, these divisions are known as 

parishes. In Alaska, which has no counties, the equivalent entities are the organized boroughs, city and 

boroughs, municipalities, and census areas; the latter of which are delineated cooperatively for statistical 

purposes by the state of Alaska and the Census Bureau. In four states (Maryland, Missouri, Nevada, and 

Virginia), there are one or more incorporated places that are independent of any county organization and 

thus constitute primary divisions of their states. These incorporated places are known as independent 

cities and are treated as equivalent entities for purposes of data presentation. The District of Columbia 

and Guam have no primary divisions, and each area is considered an equivalent entity for purposes of 
Geographic Terms and Concepts A-17

U.S. Census Bureau, 2010 Census

data presentation. All of the counties in Connecticut and Rhode Island and nine counties in Massachusetts 

were dissolved as functioning governmental entities; however, the Census Bureau continues to present 

data for these historical entities in order to provide comparable geographic units at the county level of 

the geographic hierarchy for these states and represents them as nonfunctioning legal entities in data 

products. The Census Bureau treats the following entities as equivalents of counties for purposes of data 

presentation: municipios in Puerto Rico, districts and islands in American Samoa, municipalities in the 

Commonwealth of the Northern Mariana Islands, and islands in the U.S. Virgin Islands. Each county or 

statistically equivalent entity is assigned a three-character numeric Federal Information Processing Series 

(FIPS) code based on alphabetical sequence that is unique within state and an eight-digit National Standard 

feature identifier.

COUNTY SUBDIVISION

County Subdivisions are the primary divisions of counties and equivalent entities. They include 

census county divisions, census subareas, minor civil divisions, and unorganized territories and can be 

classified as either legal or statistical. Each county subdivision is assigned a five-character numeric Federal 

Information Processing Series (FIPS) code based on alphabetical sequence within state and an eight-digit 

National Standard feature identifier.

Legal Entities

Minor civil divisions (MCDs) are the primary governmental or administrative divisions of a county in many 

states (parishes in Louisiana) and the county equivalents in Puerto Rico and the Island Areas. MCDs in 

the United States, Puerto Rico, and the Island Areas represent many different kinds of legal entities with a 

wide variety of governmental and/or administrative functions. MCDs include areas variously designated 

as barrios, barrios-pueblo, boroughs, charter townships, commissioner districts, election districts, election 

precincts, gores, grants, locations, magisterial districts, parish governing authority districts, plantations, 

purchases, reservations, supervisor’s districts, towns, and townships. The Census Bureau recognizes MCDs 

in 29 states, Puerto Rico, and the Island Areas. The District of Columbia has no primary divisions and is 

considered equivalent to an MCD for statistical purposes. (It is also considered a state equivalent and a 

county equivalent.) The 29* states in which MCDs are recognized are:

Arkansas Michigan Ohio

Connecticut Minnesota Pennsylvania

Illinois Mississippi Rhode Island

Indiana Missouri South Dakota

Iowa Nebraska Tennessee

Kansas New Hampshire Vermont

Louisiana New Jersey Virginia

Maine New York West Virginia

Maryland North Carolina Wisconsin

Massachusetts North Dakota

* Tennessee, a state with statistical census county divisions (CCDs) in 2000, reverted to MCDs in 2008.

In some states, all or some incorporated places are not part of any MCD; these places are termed 

independent places. Independent places also serve as primary legal subdivisions and have a Federal 

Information Processing Series (FIPS) county subdivision code and National Standard (ANSI) code that is 

the same as the FIPS and ANSI place code. In nine states—Maine, Massachusetts, New Hampshire, New 

Jersey, North Dakota, Pennsylvania, Rhode Island, South Dakota, and Wisconsin—all incorporated places 

are independent places. In other states, incorporated places are part of, or dependent within, the MCDs in 

which they are located, or the pattern is mixed—some incorporated places are independent of MCDs and 

others are included within one or more MCDs.

The MCDs in 12 states (Connecticut, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New 

Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Wisconsin) also serve as general-purpose 
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U.S. Census Bureau, 2010 Census

local governments that can perform the same governmental functions as incorporated places. The Census 

Bureau presents data for these MCDs in all data products for which place data are provided. 

In New York and Maine, American Indian reservations (AIRs) generally exist outside the jurisdiction of any 

town (MCD) and thus also serve as the equivalent of MCDs for purposes of data presentation.

In states with MCDs, the Census Bureau assigns a default FIPS county subdivision code of 00000 and ANSI 

code of eight zeroes in some coastal, territorial sea, and Great Lakes water where county subdivisions do 

not legally extend into the Great Lakes or out to the 3-mile limit.

Statistical Entities 

Census county divisions (CCDs) are areas delineated by the Census Bureau in cooperation with state, tribal, 

and local officials for statistical purposes. CCDs have no legal function and are not governmental units. 

CCD boundaries usually follow visible features and usually coincide with census tract boundaries. The 

name of each CCD is based on a place, county, or well-known local name that identifies its location. CCDs 

exist where:

1. There are no legally established MCDs.

2. The legally established MCDs do not have governmental or administrative purposes.

3. The boundaries of the MCDs change frequently.

4. The MCDs are not generally known to the public.

CCDs exist within the following 20* states:

Alabama Hawaii Oregon

Arizona Idaho South Carolina

California Kentucky Texas

Colorado Montana Utah

Delaware Nevada Washington

Florida New Mexico Wyoming

Georgia Oklahoma

* Tennessee, a CCD state in 2000, reverted to a MCD state in 2008.

Census subareas are statistical subdivisions of boroughs, city and boroughs, municipalities, and census 

areas, all of which are statistical equivalent entities for counties in Alaska. The state of Alaska and the 

Census Bureau cooperatively delineate the census subareas to serve as the statistical equivalents of MCDs. 

Unorganized territories (UTs) are defined by the Census Bureau in nine MCD states where portions of 

counties or equivalent entities are not included in any legally established MCD or incorporated place. The 

Census Bureau recognizes such separate pieces of territory as one or more separate county subdivisions 

for census purposes. It assigns each unorganized territory a descriptive name, followed by the designation 

“UT” and a county subdivision FIPS and ANSI code. The following states have unorganized territories:

Arkansas Maine North Carolina

Indiana Minnesota North Dakota

Iowa New York South Dakota

GEOGRAPHIC AREA ATTRIBUTES

The Census Bureau collects and maintains information describing selected attributes and characteristics of 

geographic areas. These attributes are Federal Information Processing Series (FIPS) class code, functional 

status, legal/statistical area description, internal point, and name of geographic entities.

FIPS class codes describe the general characteristics of a geographic area related to its legal or statistical 

status, governmental status, and in some cases relationship to other geographic entities. Class codes 
Geographic Terms and Concepts A-19

U.S. Census Bureau, 2010 Census

exist for counties; county subdivisions; subminor civil divisions; places; consolidated cities; Alaska Native 

Regional Corporations; American Indian, Alaska Native, and Native Hawaiian areas; and American Indian 

tribal subdivisions.

Functional status describes whether a geographic entity is a functioning governmental unit, has an inactive 

government, is an administrative area without a functioning government, or is a statistical area identified 

and defined solely for tabulation and presentation of statistical data. Functional status codes are:

A Active government providing primary general-purpose functions.

B Active government that is partially consolidated with another government but with separate officials 

providing primary general-purpose functions.

C Active government consolidated with another government with a single set of officials.

E Active government providing special-purpose functions.

F Fictitious entity created to fill the Census Bureau’s geographic hierarchy.

G Active government that is subordinate to another unit of government and thus, not considered a 

functioning government.

I Inactive governmental unit that has the power to provide primary special-purpose functions.

N Nonfunctioning legal entity.

S Statistical entity.

Internal point—The Census Bureau calculates an internal point (latitude and longitude coordinates) for 

each geographic entity. For many geographic entities, the internal point is at or near the geographic center 

of the entity. For some irregularly shaped entities (such as those shaped like a crescent), the calculated 

geographic center may be located outside the boundaries of the entity. In such instances, the internal 

point is identified as a point inside the entity boundaries nearest to the calculated geographic center and, 

if possible, within a land polygon. 

Legal/statistical area description (LSAD)—The LSAD describes the particular typology for each geographic 

entity; that is, whether the entity is a borough, city, county, town, or township, among others. For legal 

entities, the LSAD reflects the term that appears in legal documentation pertaining to the entity, such as a 

treaty, charter, legislation, resolution, or ordinance. For statistical entities, the LSAD is the term assigned 

by the Census Bureau or other agency defining the entity. The LSAD code is a two-character field that 

corresponds to a description of the legal or statistical type of entity and identifies whether the LSAD term 

should be capitalized and should precede or follow the name of the geographic entity. Note that the same 

LSAD code is assigned to entities at different levels of the geographic hierarchy when they share the same 

LSAD. For example, the Census Bureau assigns the same LSAD code (“21”) to boroughs in New York and 

Connecticut, although they are county subdivisions in the former and incorporated places in the latter. 

Name—Each geographic entity included in Census Bureau products has a name. For most geographic 

entities, the name is derived from the official legally recognized name, is assigned by local officials 

participating in Census Bureau statistical area programs, or is based on component entities and 

determined according to specified criteria. For legal entities, the name appearing in Census Bureau 

products may be the more commonly used name rather than the name as it appears in legal documents. 

For example, “Virginia” instead of “the Commonwealth of Virginia”; “Baltimore” instead of “City of 

Baltimore.” In some instances, the name for an entity in Census Bureau products will reflect the official 

name as well as a more commonly used name listed parenthetically; i.e., San Buenaventura (Ventura), CA, 

or Bath (Berkeley Springs), WV. For some types of geographic entities, the name reflected in Census Bureau 

products may be the geographic entity code assigned by local officials. For example, a census tract’s name 

is the actual number assigned by local officials, such as 1.01, whereas the census tract code would reflect 

a full four-digit base code and two-digit suffix (for example, for the preceding tract named 1.01, 000101). 
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U.S. Census Bureau, 2010 Census

GEOGRAPHIC NAMES INFORMATION SYSTEM

The Geographic Names Information System (GNIS) is the federal standard for geographic nomenclature. 

The U.S. Geological Survey (USGS) developed the GNIS for the U.S. Board on Geographic Names as the 

official repository of domestic geographic names data; the official vehicle for geographic names use by 

all departments of the federal government; and the source for applying geographic names to federal 

electronic and printed products. The GNIS contains information about physical and cultural geographic 

features of all types in the United States and its territories, current and historical, but not including roads 

and highways. The database holds the federally recognized name of each feature and defines the feature 

location by state, county, USGS topographic map, and geographic coordinates. Other attributes include 

names or spellings other than the official name, feature designations, feature classification, historical and 

descriptive information, and, for some categories, the geometric boundaries.

GEOGRAPHIC NAMES INFORMATION SYSTEM IDENTIFIER

The Geographic Names Information System Identifier (GNIS ID) is a variable length, permanent, numeric 

identifier of up to ten digits in length that identifies each entity uniquely within the nation. The GNIS is the 

new American National Standards Institute (ANSI) national standard code for several entity types. Because 

each entity’s GNIS ID is permanent, it will not change if the entity changes its name or if creation of a new 

entity changes the alphabetic sort. (Federal Information Processing Series codes are assigned based on 

the alphabetic sorting of entity names within a state and occasionally require changing codes to maintain 

the alphabetic sort.) The GNIS IDs are assigned sequentially and stored in a right-justified, variable-length, 

numeric field without leading zeroes. The GNIS now contains more than 2.6 million sequential records, 

thus no GNIS ID currently exceeds seven digits. The Census Bureau portrays the GNIS ID in its data 

products as a fixed-width eight-character field with leading zeroes.

ISLAND AREAS OF THE UNITED STATES

The Island Areas of the United States are American Samoa, Guam, the Commonwealth of the Northern 

Mariana Islands (Northern Mariana Islands), and the U.S. Virgin Islands.

The Census Bureau treats the Island Areas as entities that are statistically equivalent to states for data 

presentation purposes; data for the Island Areas, however, are presented separately from data for the 

United States and Puerto Rico. Geographic definitions specific to the Island Areas are shown in the 

appropriate publications and documentation that accompany the data products for the Island Areas. 

Sometimes the Island Areas are referred to as “Island Territories” or “Insular Areas.” For the 1990 and 

previous censuses, the U.S. Census Bureau referred to the entities as “Outlying Areas.”

Separate from the Island Areas is the term “U.S. Minor Outlying Islands.” The U.S. Minor Outlying Islands 

refers to certain small islands under U.S. jurisdiction in the Caribbean and Pacific: Baker Island, Howland 

Island, Jarvis Island, Johnston Atoll, Kingman Reef, Midway Islands, Navassa Island, Palmyra Atoll, and 

Wake Island. These areas usually are not part of standard data products.

MAF/TIGER DATABASE

MAF/TIGER is an acronym for the Master Address File/Topologically Integrated Geographic Encoding and 

Referencing system or database. It is a digital (computer-readable) geographic database that automates 

the mapping and related geographic activities required to support the Census Bureau’s census and 

survey programs. The Census Bureau developed the TIGER® system to automate the geographic support 

processes needed to meet the major geographic needs of the 1990 census: producing cartographic 

products to support data collection and map presentations, providing geographic structure for tabulation 

and dissemination of the collected statistical data, assigning residential and employer addresses to the 

correct geographic location and relating those locations to the geographic entities used for data tabulation, 

and so forth. During the 1990s, the Census Bureau developed an independent Master Address File (MAF) 

to support field operations and allocation of housing units for tabulations. After Census 2000, both the 
Geographic Terms and Concepts A-21

U.S. Census Bureau, 2010 Census

address-based MAF and geographic TIGER® databases merged to form MAF/TIGER. The content of the 

MAF/TIGER database is undergoing continuous updates and is made available to the public through a 

variety of TIGER/Line® shapefiles.

PLACE

Incorporated Places are those reported to the Census Bureau as legally in existence as of January 1, 

2010, as reported in the latest Boundary and Annexation Survey (BAS), under the laws of their respective 

states. An incorporated place is established to provide governmental functions for a concentration of 

people as opposed to a minor civil division, which generally is created to provide services or administer an 

area without regard, necessarily, to population. Places always are within a single state or equivalent entity, 

but may extend across county and county subdivision boundaries. An incorporated place usually is a city, 

town, village, or borough, but can have other legal descriptions. For Census Bureau data tabulation and 

presentation purposes, incorporated places exclude:

•	 Boroughs in Alaska (treated as statistical equivalents of counties)

•	 Towns in the New England states, New York, and Wisconsin (treated as MCDs)

•	 Boroughs in New York (treated as MCDs)

Census Designated Places (CDPs) are the statistical counterparts of incorporated places, and are 

delineated to provide data for settled concentrations of population that are identifiable by name but are 

not legally incorporated under the laws of the state in which they are located. The boundaries usually 

are defined in cooperation with local or tribal officials and generally updated prior to each decennial 

census. These boundaries, which usually coincide with visible features or the boundary of an adjacent 

incorporated place or another legal entity boundary, have no legal status, nor do these places have officials 

elected to serve traditional municipal functions. CDP boundaries may change from one decennial census 

to the next with changes in the settlement pattern; a CDP with the same name as in an earlier census does 

not necessarily have the same boundary. CDPs must be contained within a single state and may not extend 

into an incorporated place. There are no population size requirements for CDPs. 

Hawaii is the only state that has no incorporated places recognized by the Census Bureau. All places 

shown in decennial census data products for Hawaii are CDPs. By agreement with the state of Hawaii, the 

Census Bureau does not show data separately for the city of Honolulu, which is coextensive with Honolulu 

County. In Puerto Rico, which also does not have incorporated places, the Census Bureau recognizes only 

CDPs and refers to them as comunidades or zonas urbanas. Guam also has only CDPs. 

Place Codes are of two types. The five-digit Federal Information Processing Series (FIPS) place code is 

assigned based on alphabetical sequence within a state. If place names are duplicated within a state and 

they represent distinctly different areas, a separate code is assigned to each place name alphabetically 

by the primary county in which each place is located, or if both places are in the same county, they are 

assigned alphabetically by their legal descriptions (for example, “city” before “village”). Places also are 

assigned an eight-digit National Standard (ANSI) code.

Dependent and Independent Places refers to the relationship of places to the county subdivisions. 

Depending on the state, incorporated places are either dependent within, or independent of, county 

subdivisions, or there is a mixture of dependent and independent places in the state and in a county. 

Dependent places are part of the county subdivision; the county subdivision code of the place is the same 

as that of the underlying county subdivision(s) but is different from the place code. Independent places 

are not part of any minor civil division (MCD) and serve as primary county subdivisions. The independent 

place FIPS code usually is the same as that used for the MCD for the place. The only exception is if the 

place is independent of the MCDs in a state (Iowa, Louisiana, Maryland, Nebraska, North Carolina, and 

Virginia) in which the FIPS MCD codes are in the 90000 range. Then, the FIPS MCD and FIPS place codes 

will differ. CDPs always are dependent within county subdivisions and all places are dependent within 

statistical county subdivisions.
A-22 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

Consolidated City (Balance) Portions refer to the areas of a consolidated city not included in another 

separately incorporated place. For example, Butte-Silver Bow, MT, is a consolidated city (former Butte city 

and Silver Bow County) that includes the separately incorporated municipality of Walkerville city. The area 

of the consolidated city that is not in Walkerville city is assigned to Butte-Silver Bow (balance). The name 

of the area of a consolidated city not specifically within a separately incorporated place always includes 

the “(balance)” identifier. Balance portions of consolidated cities are included with other places in Census 

Bureau products.

POPULATION AND HOUSING UNIT DENSITY

Population and housing unit density are computed by dividing the total population or number of housing 

units within a geographic entity by the land area of that entity measured in square miles or in square 

kilometers. Density is expressed as “population per square mile (kilometer)” or “housing units per square 

mile (kilometer).”

PUBLIC USE MICRODATA AREAS

Public Use Microdata Areas (PUMAs) are geographic areas for which the Census Bureau provides 

selected extracts of raw data from a small sample of census records that are screened to protect 

confidentiality. These extracts are referred to as public use microdata sample (PUMS) files. 

For the 2010 Census, each state, the District of Columbia, Puerto Rico, and some Island Area participants 

delineated PUMAs for use in presenting PUMS data based on a 5 percent sample of decennial census or 

American Community Survey data. These areas are required to contain at least 100,000 people. This is 

different from Census 2000 when two types of PUMAs were defined: a 5 percent PUMA as for 2010 and an 

additional super-PUMA designed to provide a 1 percent sample. The PUMAs are identified by a five-digit 

census code unique within state.

PUERTO RICO

The Census Bureau treats the Commonwealth of Puerto Rico as the statistical equivalent of a state for data 

presentation purposes.

Municipio

The primary legal divisions of Puerto Rico are termed “municipios.” For data presentation purposes, the 

Census Bureau treats a municipio as the equivalent of a county in the United States.

Barrio, Barrio-Pueblo, and Subbarrio

The Census Bureau recognizes barrios and barrios-pueblo as the primary legal divisions of municipios. 

These entities are similar to the minor civil divisions (MCDs) used for reporting data in 29 states of the 

United States. Subbarrios in 23 municipios are the primary legal subdivisions of the barrios-pueblo and 

some barrios. The Census Bureau presents the same types of statistical data for these subminor civil 

divisions (sub-MCDs) as it does for the barrios and barrios-pueblo. (There is no geographic entity in the 

United States equivalent to the subbarrio.)

Zona Urbana and Comunidad

There are no incorporated places in Puerto Rico; instead, the Census Bureau provides data for two types of 

census designated places (CDPs): zonas urbanas, representing the governmental center of each municipio, 

and comunidades, representing other settlements. There are no minimum population size requirements for 

zonas urbanas and comunidades. 

Some types of geographic entities do not apply in Puerto Rico. For instance, Puerto Rico is not in any 

census region or census division (see also “Congressional District”).
Geographic Terms and Concepts A-23

U.S. Census Bureau, 2010 Census

SCHOOL DISTRICTS (ELEMENTARY, SECONDARY, AND UNIFIED)

School Districts are geographic entities within which state, county, local officials, the Bureau of Indian 

Affairs, or the U.S. Department of Defense provide public educational services for the area’s residents. The 

Census Bureau obtains the boundaries, names, local education agency codes, and school district levels 

for school districts from state and local school officials for the primary purpose of providing the U.S. 

Department of Education with estimates of the number of children “at risk” within each school district, 

county, and state. This information serves as the basis for the Department of Education to determine the 

annual allocation of Title I funding to states and school districts.

The Census Bureau tabulates data for three types of school districts: elementary, secondary, and unified. 

Each school district is assigned a five-digit code that is unique within state. School district codes are 

the local education agency number assigned by the Department of Education and are not necessarily in 

alphabetical order by school district name.

The elementary school districts provide education to the lower grade/age levels and the secondary school 

districts provide education to the upper grade/age levels. Unified school districts provide education to 

children of all school ages in their service areas. In general, where there is a unified school district, no 

elementary or secondary school district exists; and where there is an elementary school district, the 

secondary school district may or may not exist.

The Census Bureau’s representation of school districts in various data products is based both on the grade 

range that a school district operates and also the grade range for which the school district is financially 

responsible. For example, a school district is defined as an elementary school district if its operational 

grade range is less than the full kindergarten through 12 or prekindergarten through 12 grade range (for 

example, K–6 or pre-K–8). These elementary school districts do not provide direct educational services 

for grades 7–12, 9–12, or similar ranges. Some elementary school districts are financially responsible 

for the education of all school-aged children within their service areas and rely on other school districts 

to provide service for those grade ranges that are not operated by these elementary school districts. 

In these situations, in order to allocate all school-aged children to these school districts, the secondary 

school district code field is blank. For elementary school districts where the operational grade range and 

financially responsible grade range are the same, the secondary school district code field will contain a 

secondary school district code. There are no situations where an elementary school district does not exist 

and a secondary school district exists in Census Bureau records.

STATE OR STATISTICALLY EQUIVALENT ENTITY

States and Equivalent Entities are the primary governmental divisions of the United States. In addition 

to the 50 states, the Census Bureau treats the District of Columbia, Puerto Rico, American Samoa, the 

Commonwealth of the Northern Mariana Islands, Guam, and the U.S. Virgin Islands as the statistical 

equivalents of states for the purpose of data presentation. 

STATE LEGISLATIVE DISTRICTS (UPPER AND LOWER CHAMBERS)

State Legislative Districts (SLDs) are the areas from which members are elected to state legislatures. 

The Census Bureau first reported data for SLDs as part of the 2000 Public Law (P.L.) 94-171 Redistricting 

Data File.

Current SLDs (2010 Election Cycle)—States participating in Phase 1 of the 2010 Census Redistricting 

Data Program voluntarily provided the Census Bureau with the 2006 election cycle boundaries, codes, 

and, in some cases, names for their SLDs. All 50 states, plus the District of Columbia and Puerto Rico, 

participated in Phase 1, State Legislative District Project (SLDP) of the 2010 Census Redistricting Data 

Program. States subsequently provided legal changes to those plans through the Redistricting Data Office 

and/or corrections as part of Phase 2 of the 2010 Census Redistricting Data Program, as needed.
A-24 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

The SLDs embody the upper (senate—SLDU) and lower (house—SLDL) chambers of the state legislature. 

Nebraska has a unicameral legislature and the District of Columbia has a single council, both of which the 

Census Bureau treats as upper-chamber legislative areas for the purpose of data presentation. A unique 

three-character census code, identified by state participants, is assigned to each SLD within a state. In 

Connecticut, Hawaii, Illinois, Louisiana, Maine, Massachusetts, New Jersey, Ohio, and Puerto Rico, state 

officials did not define the SLDs to cover all of the state or state equivalent area (usually bodies of water). 

In these areas with no SLDs defined, the code “ZZZ” has been assigned, which is treated within state as a 

single SLD for purposes of data presentation. Maryland also has areas with no SLDs defined; in Maryland, 

these areas are coded with an initial “Z” by county or equivalent and treated as a unique SLD by county 

or equivalent. In Nebraska and the District of Columbia, the Census Bureau assigned the code 999 to 

represent a single SLDL where legally none exist.

SLD Names—The Census Bureau first reported names for SLDs as part of Phase 1 of the 2010 Census 

Redistricting Data Program. The SLD names with their translated legal/statistical area description are 

associated only with the current SLDs. Not all states provided names for their SLDs, therefore the code (or 

number) also serves as the name.

TRIBAL BLOCK GROUP

The 2010 tribal block group concept and criteria are completely different from those used in 2000. For 

the Census 2000, tribal block groups were the standard state-county-census tract-block group areas 

retabulated under an American Indian area hierarchy; that is, American Indian area-tribal census tracttribal block group. Tribal block groups only were applicable to legal federally recognized American Indian 

reservation and off-reservation trust land areas. Tribal block groups were defined to provide statistically 

significant sample data for small areas within American Indian areas, particularly those American Indian 

areas that crossed state or county boundaries where these boundaries were not meaningful for statistical 

purposes. The 2000 tribal block groups used the block group numbers and comprised all blocks beginning 

with a single number.

The 2010 tribal block groups are defined independently of the standard county-based block group 

delineation. For federally recognized American Indian tribes with reservations or off-reservation trust land 

and a population less than 1,200, a single tribal block group is defined. Tribal participants in qualifying 

areas with a population greater than 1,200 could define additional block groups within their reservation 

and/or off-reservation trust land without regard to the standard block group configuration.

Tribal block groups will contain blocks beginning with the same number as the standard county-based 

block group and could contain seemingly duplicate block numbers. To better identify and differentiate 

tribal block groups from county-based block groups, tribal block groups use the letter range A through K 

(except “I,” which could be confused with a number “1”) to identify and code the tribal block group. Tribal 

block groups nest within tribal census tract.

TRIBAL CENSUS TRACT

The 2010 tribal census tract concept and criteria are completely different from those used in 2000. Tribal 

census tracts (also known as tribal tracts) in 2000 were the standard state-county-census tract areas 

retabulated under an American Indian area hierarchy; that is, American Indian area-tribal census tract. 

Federally recognized tribes with a reservation or off-reservation trust land delineated tribal census tracts 

working with local census tract participants to produce a single census tract plan. Tribal census tracts were 

designed to be permanent statistical divisions of American Indian areas for the presentation of comparable 

data between censuses, particularly for those American Indian areas that crossed state or county 

boundaries where these boundaries were not meaningful for statistical purposes.

For 2010, tribal census tracts are defined independently of the standard county-based tract delineation. 

For federally recognized American Indian tribes with reservations or off-reservation trust land and a 
Geographic Terms and Concepts A-25

U.S. Census Bureau, 2010 Census

population less than 2,400, a single tribal census tract is defined. Qualifying areas with a population 

greater than 2,400 could define additional tribal census tracts within their area.

In 2000, the tract number range of 9400 through 9499 was reserved for tribal census tracts and was 

required for those tribal census tracts that crossed state or county boundaries. Not all tribal census tracts 

in 2000, however, used this range. For 2010, tribal census tract codes will be six characters long with a 

leading “T” alphabetic character followed by five numeric codes having an implied decimal between the 

fourth and fifth character; for example, T01000, which translates as tribal census tract 10. Tribal block 

groups will nest within tribal census tract. Since individual blocks are defined within the standard statecounty-census tract hierarchy, a tribal census tract can contain seemingly duplicate block numbers, thus 

tribal census tracts cannot be used to uniquely identify census blocks.

UNITED STATES

The United States consists of the 50 states and the District of Columbia.

URBAN AND RURAL

For the 2010 Census, the Census Bureau classified as urban all territory, population, and housing units 

located within urbanized areas (UAs) and urban clusters (UCs), both defined using the same criteria. The 

Census Bureau delineates UA and UC boundaries that represent densely developed territory, encompassing 

residential, commercial, and other nonresidential urban land uses. In general, this territory consists of 

areas of high population density and urban land use resulting in a representation of the “urban footprint.” 

Rural consists of all territory, population, and housing units located outside UAs and UCs. 

For the 2010 Census, the urban and rural classification was applied to the 50 states, the District of 

Columbia, Puerto Rico, American Samoa, Guam, the Commonwealth of the Northern Mariana Islands, and 

the U.S. Virgin Islands.

Urbanized Areas (UAs)—An urbanized area consists of densely developed territory that contains 50,000 

or more people. The Census Bureau delineates UAs to provide a better separation of urban and rural 

territory, population, and housing in the vicinity of large places. 

Urban Clusters (UCs)—An urban cluster consists of densely developed territory that has at least 2,500 

people but fewer than 50,000 people. The Census Bureau first introduced the UC concept for Census 2000 

to provide a more consistent and accurate measure of urban population, housing, and territory throughout 

the United States, Puerto Rico, and the Island Areas.

Urban Area Titles and Codes—The title of each UA and UC may contain up to three incorporated place 

or census designated place (CDP) names and will include the two-letter U.S. Postal Service abbreviation 

for each state or statistically equivalent entity into which the UA or UC extends. However, if the UA or UC 

does not contain an incorporated place or CDP, the urban area title will include the single name of a minor 

civil division or populated place recognized by the U.S. Geological Survey’s Geographic Names Information 

System.

Each UC and UA is assigned a five-digit numeric census code based on a national alphabetical sequence of 

all urban area names. A separate flag is included in data tabulation files to differentiate between UAs and 

UCs. In printed reports, this differentiation is included in the name.

Central Place—The 2010 Census urban areas will no longer include one or more designated central 

places. In preceding censuses, the central place included all incorporated or census designated places 

included in the urban area title, plus additional incorporated areas that met a population size criterion. The 

concept of central place for urban areas no longer is being applied.

Relationship to Other Geographic Entities—Geographic entities, such as metropolitan areas, counties, 

minor civil divisions, places, and census tracts, often contain both urban and rural territory, population, 

and housing units.
A-26 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

URBAN GROWTH AREAS

Urban Growth Areas (UGAs) are legally defined entities in Oregon and Washington that the Census 

Bureau includes in the MAF/TIGER database in agreement with the states. UGAs, which are defined around 

incorporated places, are used to regulate urban growth. UGA boundaries, which need not follow visible 

features, are delineated cooperatively by state and local officials and then confirmed in state law. UGAs are 

a pilot project first defined only in Oregon for Census 2000. Each UGA is identified by a five-digit numeric 

census code, usually the same as the five-digit Federal Information Processing Series (FIPS) code associated 

with the incorporated place for which the UGA is named.

VOTING DISTRICTS

Voting Districts (VTDs) refer to the generic name for geographic entities, such as precincts, wards, 

and election districts, established by state governments for the purpose of conducting elections. States 

voluntarily participating in Phase 2 of the 2010 Census Redistricting Data Program provided the Census 

Bureau with boundaries, codes, and names for their VTDs. Each VTD is identified by a one-to-six-character 

alphanumeric census code that is unique within county. The code “ZZZZZZ” identifies a portion of counties 

(usually bodies of water) for which no VTDs were identified. For the 2010 Census, only Rhode Island did 

not participate in Phase 2 (the Voting District/Block Boundary Suggestion Project) of the 2010 Census 

Redistricting Data Program. Kentucky chose not to provide VTDs as part of their participation in Phase 2, 

and the states of Montana and Oregon provided VTDs for some counties. Therefore, for 2010 Census data 

products, no VTDs exist in select counties in Montana and Oregon or for the states of Rhode Island and 

Kentucky in their entirety. Participating states often submitted VTDs conforming to the feature network 

in the MAF/TIGER database rather than the complete legal boundary of the VTD. If requested by the 

participating state, the Census Bureau identified the VTDs that represent an actual voting district with an “A” 

in the voting district indicator field. Where a participating state indicated that the VTD has been modified to 

follow existing features, the VTD is a pseudo-VTD, and the voting district indicator contains “P.” 

ZIP CODE TABULATION AREAS

ZIP Code Tabulation Areas (ZCTAs) are approximate area representations of U.S. Postal Service (USPS) 

five-digit ZIP Code service areas that the Census Bureau creates using whole blocks to present statistical 

data from censuses and surveys. The Census Bureau defines ZCTAs by allocating each block that contains 

addresses to a single ZCTA, usually to the ZCTA that reflects the most frequently occurring ZIP Code 

for the addresses within that tabulation block. Blocks that do not contain addresses but are completely 

surrounded by a single ZCTA (enclaves) are assigned to the surrounding ZCTA; those surrounded by 

multiple ZCTAs will be added to a single ZCTA based on limited buffering performed between multiple 

ZCTAs. The Census Bureau identifies five-digit ZCTAs using a five-character numeric code that represents 

the most frequently occurring USPS ZIP Code within that ZCTA, and this code may contain leading zeros.

There are significant changes to the 2010 ZCTA delineation from that used in 2000. Coverage was 

extended to include the Island Areas for 2010 so that the United States, Puerto Rico, and the Island Areas 

have ZCTAs. Unlike 2000, when areas that could not be assigned to a ZCTA were given a generic code 

ending in “XX” (land area) or “HH” (water area), for 2010 there is no universal coverage by ZCTAs, and 

only legitimate five-digit areas are defined. The 2010 ZCTAs will better represent the actual Zip Code 

service areas because the Census Bureau initiated a process before creation of 2010 blocks to add block 

boundaries that split polygons with large numbers of addresses using different Zip Codes.

Data users should not use ZCTAs to identify the official USPS ZIP Code for mail delivery. The USPS makes 

periodic changes to ZIP Codes to support more efficient mail delivery. The ZCTAs process used primarily 

residential addresses and was biased towards Zip Codes used for city-style mail delivery, thus there may 

be Zip Codes that are primarily nonresidential or boxes only that may not have a corresponding ZCTA.
Geographic Terms and Concepts A-27

U.S. Census Bureau, 2010 Census

Figure A-1. 

Standard Hierarchy of Census Geographic Entities
A-28 Geographic Terms and Concepts

U.S. Census Bureau, 2010 Census

Figure A-2.

Hierarchy of American Indian, Alaska Native, and Native Hawaiian Areas

American Indian Areas (Federal)/

Off-Reservation Trust Lands

States Tribal Designated Statistical Areas

Hierarchy of American Indian, Alaska Native, and Native Hawaiian Areas

Tribal Census Tracts Oklahoma Tribal

Statistical Areas

Alaska Native Regional Corporations /

Alaska Native Village Statistical Areas /

Hawaiian Home Lands

American Indian Reservations (state) /

State Designated Tribal Statistical Areas

Tribal Block Groups Tribal Subdivisions

C E N S U S B L O C K S
Geographic Terms and Concepts A-29

U.S. Census Bureau, 2010 Census

Figure A-3. 

Census Regions, Census Divisions, and Their Constituent States

Northeast Region

New England Division:

Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut

Middle Atlantic Division:

New York, New Jersey, Pennsylvania

Midwest Region

East North Central Division:

Ohio, Indiana, Illinois, Michigan, Wisconsin

West North Central Division:

Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, Kansas

South Region

South Atlantic Division:

Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina,

Georgia, Florida

East South Central Division:

Kentucky, Tennessee, Alabama, Mississippi

West South Central Division:

Arkansas, Louisiana, Oklahoma, Texas

West Region

Mountain Division:

Montana, Idaho, Wyoming, Colorado, New Mexico, Arizona, Utah, Nevada

Pacific Division:

Washington, Oregon, California, Alaska, Hawaii

Definitions of Subject Characteristics B-1

U.S. Census Bureau, 2010 Census

Appendix B.

Definitions of Subject Characteristics

CONTENTS

Population. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Living Quarters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Housing Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

 Occupied Housing Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

 Vacant Housing Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

 Housing for the Older Population. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3

Group Quarters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3

Derived Measures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4

Area Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4

Average (Mean) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4

Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4

Percentage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4

POPULATION 

The 2010 Census data products provide, except where specifically noted, counts of the resident 

population of the United States. The U.S. resident population includes everyone whose usual place of 

residence was in the 50 states and the District of Columbia at the time of the 2010 Census. In addition to 

the resident population, this report series also contains a report for Puerto Rico and includes Puerto Rico 

data at the end of many of the tables in the summary report for the United States.

In this report, total population counts (the sum of all people living in housing units and group quarters) are 

presented for various geographic entities. Separate population characteristics (e.g., age, gender, or race) 

are not shown.

LIVING QUARTERS 

All living quarters are classified as either housing units or group quarters. Living quarters are usually 

found in structures that are intended for residential use, but also may be found in structures intended 

for nonresidential use. Any place where someone lives is considered to be a living quarters, such as an 

apartment, a dormitory, a shelter for people experiencing homelessness, a barracks, or a nursing facility. 

Even tents, old railroad cars, and boats are considered to be living quarters if someone claims them as his 

or her residence. Note that structures that do not meet the definition of a living quarters at the time of 

listing may meet the definition at the time of enumeration. Some types of structures, such as those cited in 

items 1 and 2 below, are included in address canvassing operations as placeholders, with the final decision 

on their living quarters’ status made during enumeration. Other types of structures, such as those cited in 

items 3 and 4 below, are not included in the address canvassing operation. 

The following examples are not considered living quarters.

1. Structures, such as houses and apartments, that resemble living quarters but are being used entirely 

for nonresidential purposes, such as a store or an office, or used for the storage of business supplies or 

inventory, machinery, or agricultural products are not enumerated. 

2. Single units as well as units in multiunit residential structures under construction in which no one is 

living or staying are not considered living quarters until construction has reached the point where all 

exterior windows and doors are installed and final usable floors are in place. Units that do not meet 

these criteria are not enumerated. 
B-2 Definitions of Subject Characteristics

U.S. Census Bureau, 2010 Census 

3. Structures in which no one is living or staying that are open to the elements—that is, the roof, walls, 

windows, and/or doors no longer protect the interior from the elements—are not enumerated. Also, 

vacant structures with a posted sign indicating that they are condemned or they are to be demolished 

are not enumerated.

4. Boats, recreational vehicles (RVs), tents, caves, and similar types of shelter that no one is using as a 

usual residence are not considered living quarters and are not enumerated. 

Housing Units

A housing unit is a living quarters in which the occupant or occupants live separately from any other 

individuals in the building and have direct access to their living quarters from outside the building or 

through a common hall. Housing units are usually houses, apartments, mobile homes, groups of rooms, or 

single rooms that are occupied as separate living quarters. They are residences for single individuals, for 

groups of individuals, or for families who live together. A single individual or a group living in a housing 

unit is defined to be a household. Additional details about housing for the elderly population and group 

homes are provided in the section “Housing for the Older Population.”

For vacant housing units, the criteria of separateness and direct access are applied to the intended 

occupants whenever possible. Nontraditional living quarters, such as boats, RVs, and tents, are considered 

to be housing units only if someone is living in them and they are either the occupant’s usual residence 

or the occupant has no usual residence elsewhere. These nontraditional living arrangements are not 

considered to be housing units if they are vacant.

Housing units are classified as being either occupied or vacant. 

Occupied Housing Unit—A housing unit is classified as occupied if it is the usual place of residence of 

the individual or group of individuals living in it on Census Day, or if the occupants are only temporarily 

absent, such as away on vacation, in the hospital for a short stay, or on a business trip, and will be 

returning.

The occupants may be one individual, a single family, two or more families living together, or any other 

group of related or unrelated individuals who share living arrangements.

Occupied rooms or suites of rooms in hotels, motels, and similar places are classified as housing units 

only when occupied by permanent residents; that is, occupied by individuals who consider the hotel their 

usual place of residence or who have no usual place of residence elsewhere. However, when rooms in 

hotels and motels are used to provide shelter for people experiencing homelessness, they are not housing 

units. Rooms used in this way are considered group quarters.

Vacant Housing Unit—A housing unit is classified as vacant if no one is living in it on Census Day, unless 

its occupant or occupants are only temporarily absent—such as away on vacation, in the hospital for a 

short stay, or on a business trip—and will be returning.

Housing units temporarily occupied at the time of enumeration entirely by individuals who have a usual 

residence elsewhere are classified as vacant. When housing units are vacant, the criteria of separateness 

and direct access are applied to the intended occupants whenever possible. If that information cannot be 

obtained, the criteria are applied to the previous occupants.

Boats, RVs, tents, caves, and similar shelter that no one is using as a usual residence are not considered 

living quarters and, therefore, are not enumerated at all.
Definitions of Subject Characteristics B-3

U.S. Census Bureau, 2010 Census

Housing for the Older Population—Housing specifically for the older population has become more 

and more prevalent and is being identified by many different names. Living quarters in these facilities, 

unless they meet the definition of skilled-nursing facilities, are housing units, with each resident’s living 

quarters considered a separate housing unit if it meets the housing unit definition of direct access. These 

residential facilities may be referred to as senior apartments, active adult communities, congregate care, 

continuing care retirement communities, independent living, board and care, or assisted living. People may 

have to meet certain criteria to be able to live in these facilities, but once accepted as residents, they have 

unrestricted access to and from their units to the outside.

Housing units and group quarters may coexist under the same entity or organization and in some 

situations actually share the same structure. An assisted living facility complex may have a skilled-nursing 

floor or wing that meets the definition of a nursing facility and is, therefore, a group quarters, while the 

rest of the living quarters in the facility are considered to be housing units. Congregate care facilities 

and continuing care retirement communities often consist of several different types of living quarters, 

with varying services and levels of care. Some of the living quarters in these facilities and communities 

are considered to be housing units, and some are considered to be group quarters, depending on which 

definition they meet.

Comparability. The first Census of Housing in 1940 established the “dwelling unit” concept. Although the 

term became “housing unit” and the definition was modified slightly in succeeding censuses, the housing 

unit definition remained essentially comparable between 1940 and 1990. Since 1990, two changes were 

made to the housing unit definition. 

The first change eliminated the concept of “eating separately.” The elimination of the eating criterion is 

more in keeping with the United Nations’ definition of a housing unit that stresses the entire concept of 

separateness rather than the specific “eating” element. Although the “eating separately” criterion previously 

was included in the definition of a housing unit, the data needed to distinguish whether the occupants ate 

separately from any other people in the building were not collected. (Questions that asked households 

about their eating arrangements have not been included in the census since 1970.) Therefore, the current 

definition better reflects the information that is used in the determination of a housing unit. 

The second change for Census 2000 and the 2010 Census eliminated the “number of nonrelatives” 

criterion; that is, “9 or more people unrelated to the householder,” which caused a conversion of housing 

units to group quarters. This change was prompted by the following considerations: (1) there were 

relatively few such conversions made as a result of this rule in 1990; (2) household relationship and 

housing data were lost by converting these units to group quarters; and (3) there was no empirical support 

for establishing a particular number of nonrelatives as a threshold for these conversions. 

In 1960, 1970, and 1980, vacant rooms in hotels, motels, and other similar places where 75 percent or 

more of the accommodations were occupied by permanent residents were counted as part of the housing 

inventory. However, an evaluation of the data collection procedures prior to the 1990 Census indicated 

that the concept of permanency was a difficult and confusing procedure for enumerators to apply correctly. 

Consequently, in the 1990 Census, vacant rooms in hotels, motels, and similar places were not counted as 

housing units. In Census 2000 and the 2010 Census, we continued the procedure adopted in 1990. 

Group Quarters

Group quarters are places where people live or stay in a group living arrangement that are owned or 

managed by an entity or organization providing housing and/or services for the residents. This is not a 

typical household-type living arrangement. These services may include custodial or medical care as well as 

other types of assistance, and residency is commonly restricted to those receiving these services. People 

living in group quarters are usually not related to each other. 

Group quarters include such places as college residence halls, residential treatment centers, skillednursing facilities, group homes, military barracks, correctional facilities, and workers’ dormitories.
B-4 Definitions of Subject Characteristics

U.S. Census Bureau, 2010 Census 

Comparability. Like in Census 2000, rooming and boarding houses are classified as housing units in the 

2010 Census. In the 1990 Census, these were considered group quarters.

DERIVED MEASURES

Census data products include various derived measures, such as medians, means, and percentages, as well 

as certain rates and ratios. Derived measures that round to less than 0.1 are not shown but indicated as 

zero. Zero is indicated by showing a dash (–).

Area Measurement

Area measurements (land area, water area, and total area) provide the size of geographic entities. Total 

area is the sum of land area and water area. In this report series, area measurements are displayed in 

square miles after being converted from square meters by dividing by 2,589,988.

Average (Mean)

This measure represents an arithmetic average of a set of values. It is derived by dividing the sum (or 

aggregate) of a group of numerical items by the total number of items in that group. For example, average 

population or housing units per square mile (see “Density”) is computed by dividing the total population or 

number of housing units within a geographic entity (for example, United States, state, county, place) by the 

land area of that entity measured in square miles (see “Area Measurement”).

Density

Population density (average number of people per square mile) is calculated by dividing the number of 

people in a specified geographic area by its land area in square miles. 

Housing unit density (average number of housing units per square mile) is calculated by dividing the 

number of housing units in a specified geographic area by its land area in square miles.

In this report series, 2010 Census density is calculated from land area after it is converted to square miles 

(see “Area Measurement”) and rounded to two decimal places. When density is shown for older decades 

(which only occurs in the summary report for the United States), the values are shown exactly as they were 

in the Census 2000 PHC-3 series.

Percentage

This measure is calculated by taking the number of items in a group possessing a characteristic of interest 

and dividing by the total number of items in that group, and then multiplying by 100.
Data Collection and Processing Procedures C-1

U.S. Census Bureau, 2010 Census

Appendix C.

Data Collection and Processing Procedures

CONTENTS

2010 Census Mission and Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

Six Operational Planning Categories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

1. Provide Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

2. Establish Where to Count. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

3. Collect and Integrate Respondent Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4

4. Provide Census Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-5

5. Measure Census Coverage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-5

6. Analyze and Research the Census. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-6

Thumbnail Descriptions of 2010 Census Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-7

Timeline of 2010 Census Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-9

Lists of States’ Services by Each Regional Office. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-10 

2010 CENSUS MISSION AND SCOPE

Beginning with the Congressional Act of March 6, 1902, the U.S. Census Bureau was legally established as 

the “official” data collector for the United States of America. The Census Bureau routinely conducts multiple 

national, large-scale household surveys and censuses to provide the Administration; Congress; state, local, 

and tribal planners; the business community; trade associations; academicians; and other data users with 

a vast array of essential information. Most notable is the every 10-year (decennial) census of population 

and housing.

This section provides an overview of operations and systems in the 2010 Census of Population and 

Housing. To assist in understanding terms in the descriptions of many operations or to learn more 

about the 2010 Census, please refer to <www.2010census.gov> or the official 2010 Census glossary of 

acronyms, where detailed definitions of terms and acronyms can be found at <www.census.gov/dmd

/www/glossary.html>. Thumbnail descriptions are found in this section as well as the operational timeline 

for the operations and the contact information for the 12 regional offices.

The mission, upon which we define the requirements and build the systems, is “the 2010 Census will 

conduct a census of population and housing, and disseminate the data to the President, the States, and to 

the American people.” The scope of the 2010 Census is as follows: 

•	 The 2010 Census shall cover the 50 states, the District of Columbia, Puerto Rico, the U.S. Virgin

Islands, the Commonwealth of the Northern Mariana Islands, Guam, the Pacific Island Area of American 

Samoa, and Federally Affiliated Americans overseas.

•	 The Census Day for the 2010 Census shall be April 1, 2010; have a boundary reference date of January

1, 2010; and deliver apportionment counts to the President by December 31, 2010, and redistricting 

counts to the states by April 1, 2011. 

•	 The 2010 Census concludes upon delivery of all products and the subsequent headquarters closeout

activities ending September 30, 2013.

The focus of this section is the 2010 Census. It does not include descriptions of the American Community 

Survey or the Master Address File/Topographically Integrated Geographic Encoding and Referencing

(MAF/TIGER®) database Enhancement Program. It should also be noted that from a strategy and 
C-2 Data Collection and Processing Procedures

U.S. Census Bureau, 2010 Census

operational perspective, Puerto Rico is treated the same as the 50 States and the District of Columbia, with 

the exception of language (Spanish) and minor program modifications. 

SIX OPERATIONAL PLANNING CATEGORIES

The forty-four 2010 Census operations and operation groups are categorized into 1 of the 6 categories 

based on the similarity of their missions. High-level descriptions of the operational planning categories are: 

1. Provide Support—This category is concerned with supporting operations of the 2010 Census 

through the organization and operation of the census business processes that make the census 

mission possible. Activities include operational support, planning and management support, as 

well as infrastructure support and system design, development, and testing.

2. Establish Where to Count—This category is concerned with gathering and compiling the 

needed inputs to ensure the completeness of the geographic and address data that make up 

the framework for the census, as well as establishing the respondent data collection universe 

for the census itself. These activities provide the basis for the work done to collect respondent 

information.

3. Collect and Integrate Respondent Information—This category is concerned with the actual 

collection of census respondent information as derived through processing completed census 

forms delivered by the U.S. Postal Service or gathered through field enumeration activities.

4. Provide Census Results—This category is concerned with the refinement of collected census 

response data and dissemination of census results. Response data collected from census forms 

processing and field enumeration are refined and edited to produce an accurate count with 

complete data characteristics. These counts with characteristic data are then summarized, which 

removes personally identifiable information. A wide array of census products are then produced 

and disseminated.

5. Measure Census Coverage—This category includes coverage measurement operations that are 

separate from and independent of the census operations. They are designed to provide estimates 

of net coverage error and omissions and erroneous enumerations for persons in housing units and 

for the housing units themselves. These activities provide the needed inputs, which allow census 

coverage to be measured.

6. Analyze and Research the Census—This category includes 2010 Census assessments, 

evaluations, and experiments. Assessments are used to document final volumes and rates for 

individual operations or processes, using data from production files and activities; quality control 

files and activities; and information collected from debriefings and lessons learned. Evaluations 

analyze the outcomes of pre-specified census operations, such as the effectiveness of integrated 

communications. Experiments are studies that occur during the census to learn about new or 

different methodologies which inform the 2020 Census design.

1. Provide Support

The Provide Support operational planning category includes the operations that sustain the 2010 Census 

through activities that allow the data collection operations to run smoothly and efficiently. These activities 

include planning and management support, security, public communications, language translation, 

materials support, infrastructure support, and management of system design, development, and 

deployment.

1. 2010 Census Management Operations—Responsible for the planning and implementation of 

all 2010 Census operations.
Data Collection and Processing Procedures C-3

U.S. Census Bureau, 2010 Census 

2. Content and Forms Design Operation—Responsible for the design and content of 

questionnaires and other materials in order to generate high and consistent response rates across 

all 2010 Census operations.

3. Security, Privacy, and Confidentiality Operations—Ensures that all 2010 Census operations 

adhere to the appropriate security, privacy, and confidentiality policies and regulations.

4. Field Infrastructure Support Operations—Supports all 2010 Census field data collection 

operations through staffing, office space and computing infrastructure deployment and support, 

and supply and material distribution.

5. Language Services Operations—Supports the language needs of the 2010 Census operations 

by translating materials to the over 40 languages targeted for 2010 Census.

6. Integrated Communications Services Operation—Responsible for educating, creating 

awareness and motivating persons to participate by responding to the 2010 Census.

2. Establish Where to Count

The Establish Where to Count operational planning category includes the operations that perform activities 

to gather and compile the geographic and address data that make up the framework for the 2010 Census. 

This includes activities that create and manage the respondent data collection universes for the census 

data collection operations.

7. Geographic Updating and Delineation Operation—Determines, delineates, and updates the 

geographic area boundaries for data collection.

8. Administrative Records Updating Operation—Uses administrative records sources from 

the U.S. Postal Service (USPS), local governments, and independent organizations to ensure the 

address list is as complete as possible.

9. Local Update of Census Addresses (LUCA) Operation—Provides the opportunity for tribal, 

state, and local governments to review and comment on the Census Bureau’s address list to ensure 

an accurate and complete enumeration of their communities.

10. New Construction Operation—Provides the opportunity for tribal and local governments to 

report newly constructed living quarters in the enumeration areas where the Census Bureau 

delivers questionnaires using the USPS.

11. Address Canvassing Field Operation—Collects updated living quarters addresses, geographic 

features, and spatial information, including the verified LUCA updates.

12. Group Quarters Validation Field Operation—Classifies “Other Living Quarters” as a group 

quarters or non-group quarters, then assigns a group quarters type code which will be utilized by 

other operations.

13. Update/Leave Operation—For geographic areas where mail delivery problems are anticipated, 

Update/Leave field operations hand deliver questionnaires to housing units and update address 

lists and maps if inconsistencies are found.

14. Field Verification Field Operation—Verifies the existence of respondent-provided housing unit 

addresses that have not been confirmed by a Census Bureau employee and also verifies potential 

duplicate housing units identified in Response Processing.

15. Non-ID Processing Operation—Associates census identification numbers with completed 

respondent-generated questionnaires that do not have a preassigned census identification number 

but have a respondent-provided address.
C-4 Data Collection and Processing Procedures

U.S. Census Bureau, 2010 Census

16. Geographic Data Processing Production (GDP) Operation—Maintains the MAF/TIGER® 

system, which is the repository for spatial and address data, and provides spatial and address 

products for 2010 Census operations.

17. Universe Control and Management Production Operation—Creates and manages the 

respondent data collection universes for census data collection operations using a database of 

GDP-provided census addresses and related information.

3. Collect and Integrate Respondent Information

The Collect and Integrate Respondent Information operational planning category includes the operations 

that collect census respondent information through processing completed census forms delivered by the 

USPS or gathered through field enumeration activities.

18. Forms Printing and Distribution Operation—Prints all public-use forms and other materials 

to support the 2010 Census, including the 2010 Census questionnaire mailed to housing units on 

March 15, 2010.

19. Update Enumerate Operation—Updates the address list and enumerates the housing units in 

certain designated geographic areas with special enumeration needs. This group includes the 

Remote Update Enumeration and Remote Alaska operations. 

20. Enumeration at Transitory Locations Field Operation—Enumerates individuals that do not 

have a usual home elsewhere (UHE) at housing units at transitory locations.

21. Be Counted/Questionnaire Assistance Center Operation—Provides community outreach in 

hard to enumerate (HTE) areas to assist persons in completing their census questionnaire.

22. Invalid Return Detection Operation—Detects potentially fraudulent returns.

23. Nonreponse Operation—Enumerates all housing units that did not respond to the mailed out 

census questionnaire. 

24. Coverage Follow-Up Operation—A telephone operation that resolves erroneous enumerations 

and omissions detected from other enumeration operations. 

25. Group Quarters Operation—Establishes contacts and enumerates individuals at Group Quarters 

locations. This operation group includes both Group Quarters Advance Visit and Group Quarters 

Enumeration (which itself includes Service-Based Enumeration, Military Group Enumeration, and 

Domestic Military/Maritime Vessels Enumeration operations).

26. Island Areas Enumeration Operation—Lists all residential and other living quarters and 

enumerates these units in American Samoa, the Commonwealth of the Northern Mariana Islands, 

Guam, and the U.S. Virgin Islands.

27. Federally Affiliated Americans Overseas Count Operation—Obtains counts of U.S. military 

and federal civilian employees stationed overseas and their dependents living with them that 

can be allocated to a home state for the purposes of reapportioning seats in the U.S. House of 

Representatives.

28. Telephone Questionnaire Assistance and Fulfillment Operation—Provides assistance over 

the phone to 2010 Census callers.

29. Data Capture and Integration (DCI) Operation—Provides a means to capture both 

questionnaire data and geographic data from data collection operations and integrates them into a 

common set of formats for further processing. 
Data Collection and Processing Procedures C-5

U.S. Census Bureau, 2010 Census 

4. Provide Census Results

The Provide Census Results operational planning category is concerned with the refinement of the 

collected census response data and dissemination of census results. Response data collected from census 

forms processing and field enumeration are refined and edited to produce an accurate count with complete 

data characteristics. These counts with characteristic data are then summarized, which removes personally 

identifiable information. A wide array of census products are then produced and disseminated.

30. Geographic Boundary and Districting Operation—Determines and updates the geographic 

area boundaries for districting and tabulation. 

31. Response Processing Production Operation—Processes integrated response data provided 

by the DCI operation to unduplicate responses, ensure that complete information is collected, 

conduct statistical methods, and format data files used to produce census results.

32. Count Review Operation—Designed to enhance the accuracy of the census and provides the 

Federal-State Cooperative Program for Population Estimates (FSCPE) with the opportunity to review 

and provide feedback on count tabulations prior to the release of Public Law 94-171 data.

33. Data Products and Dissemination Production (DPD) Operation—Tabulates and disseminates 

2010 Census products, including apportionment counts and Public Law 94-171 redistricting data. 

The DPD produces many data products, including state and national summary files, tabulated 

informational files, and data comparison tables. The DPD is responsible for printed and electronic 

informational products that include population and housing unit tabulations, geographical maps, 

and a number of data products that specifically pertain to the island areas. 

The Data Access and Dissemination System (DADS) program is the primary provider of 

dissemination services via the Internet through the American FactFinder (AFF) system. This 

system was redesigned and enhanced for the 2010 Census and for dissemination of other Census 

Bureau data products. The DADS program is also the provider of tabulation services for the 

decennial census. Tabulation services refer to the activities related to aggregating data collected 

on individual responses to a survey or census into summarized statistical data suitable for public 

release. Dissemination services refer to the activities related to the internal staging and release 

of approved statistics for posting on the Internet. These services include the provision of interim 

results or output so that other areas of the Census Bureau can process and release data in different 

media and formats, (e.g. CD-ROM, DVD, File Transfer Protocol [FTP], Adobe Acrobat Portable 

Document Format [PDF] for printed publications). 

34. Archiving Operation—Provides 2010 Census records to the National Archives and Records 

Administration (NARA).

5. Measure Census Coverage

The Measure Census Coverage operational planning category includes coverage measurement operations 

that are separate from and independent of the census operations. They are designed to provide estimates 

of net coverage error and omissions and erroneous enumerations for persons in housing units and for the 

housing units themselves. These activities provide the needed inputs that allow census coverage to be 

measured. This planning category consists of the Census Coverage Measurement (CCM) program and the 

Demographic Analysis operation.

The focus of the CCM program is to measure the coverage error in the 2010 Census with the goal of 

improving future census operations. CCM produces estimates of net coverage error and estimates of 

the coverage error components for both housing units and persons living in housing units. Components 

of coverage error include omissions and erroneous enumerations (including duplicates). Measuring the 

coverage error of persons in group quarters and of group quarters facilities is not within the scope of the 
C-6 Data Collection and Processing Procedures

U.S. Census Bureau, 2010 Census

CCM program. The CCM is a sample survey and, as is typical, is conducted separately and independently 

of the census operations to ensure that the coverage error estimates are unbiased.

35. CCM Sample Design Operation—Designs and implements the sample to support the estimation 

of coverage errors in the 2010 Census for the United States and Puerto Rico, excluding remote 

Alaska. 

36. CCM Independent Listing Field Operation—Creates the list of CCM addresses by canvassing 

the selected sample block cluster areas using a paper instrument called the CCM Independent 

Listing Book (ILB).

37. CCM Initial Housing Unit Matching and Follow-Up Operation—Determines the reasons for 

differences between the housing unit addresses in the CCM sample and the initial census address 

list using automated computer matching, clerical matching, and in-person follow-up techniques.

38. CCM Person Interview Field Operation—Collects person and housing unit information for 

selected housing units in each sample block cluster by performing in-person interviews using a 

computer-assisted data collection instrument.

39. CCM Person Matching and Follow-Up Operation—Determines the reasons for the differences 

between the persons in the CCM sample and the persons in the 2010 Census using automated 

computer matching, clerical matching, telephone and in-person follow-up techniques.

40. CCM Final Housing Unit Matching and Follow-Up Operation—Determines the reasons for 

the differences between the housing unit addresses in the CCM sample and the final 2010 Census 

address list using automated computer matching, clerical matching, and in-person follow-up 

techniques.

41. CCM Estimation Operation—Produces estimates of net coverage error and the components 

of coverage error for housing units and persons living in housing units in the United States and 

Puerto Rico, excluding remote Alaska.

42. Demographic Analysis Operation—Produces independent assessments of census coverage 

using population and housing unit benchmarks in support of the 2010 Census and the evaluation 

of 2010 Census results.

6. Analyze and Research the Census

The Analyze and Research the Census operational planning category includes 2010 Census assessments, 

evaluations, and experiments. Assessments are used to document final volumes and rates for individual 

operations or processes, using data from production files and activities; quality control files and activities; 

and information collected from debriefings and lessons learned. Evaluations analyze the outcomes of 

prespecified census operations, such as the effectiveness of integrated communications. Experiments are 

studies that occur during the census to learn about new or different methodologies, which inform the 

2020 Census design.

43. Evaluations, Experiments, and Assessments Operation—Includes all of the analyses of 

the design and operations of the 2010 Census, as well as experimental design changes that 

could inform the 2020 Census. Evaluations and assessments are performed and experiments are 

conducted to analyze the 2010 Census and to inform early research in the 2020 Census test cycle.

44. Count Question Resolution Operation—Conducts an administrative review to handle 

external challenges to official 2010 Census counts of housing units and group quarters and their 

associated population.
Data Collection and Processing Procedures C-7

U.S. Census Bureau, 2010 Census 

THUMBNAIL DESCRIPTIONS OF 2010 CENSUS OPERATIONS

Address Canvassing—A field operation where census workers systematically canvass all census 

blocks looking for living quarters and updating the address and map information on a hand-held 

computer. 

Be Counted Program—A program designed for persons who believe they were not counted in 

the 2010 Census. The Census Bureau will place unaddressed census questionnaires at selected 

public sites so that individuals that did not receive one in the mail can complete the census.

Census Coverage Follow-Up—A census operation designed to ensure that no person is left out 

or counted in more than one place in the census and to clarify responses previously collected to 

improve the accuracy of the census.

Census Coverage Measurement (CCM) Final Housing Unit Follow-Up—A coverage 

measurement field operation designed to gather additional information to determine reasons for 

differences between the Independent Listing operation and census records.

Census Coverage Measurement (CCM) Independent Listing Operation—A coverage 

measurement field operation to construct a list of all housing units, independent of the census, 

contained within select CCM block clusters.

Census Coverage Measurement (CCM) Initial Housing Unit Follow-Up—A coverage 

measurement field operation designed to gather information to determine reasons for differences 

between the Independent Listing operation results and the preliminary census address file.

Census Coverage Measurement (CCM) Person Follow-Up—A coverage measurement field 

operation designed to collect additional information about persons or households to determine 

reasons for differences between the CCM Person Interview and the census enumeration. 

Census Coverage Measurement (CCM) Person Interview—A coverage measurement field 

operation designed to collect information about the current resident(s) of each sample housing 

unit and certain persons who had moved out of the sample address between Census Day and the 

time of the CCM Person Interview.

Enumeration at Transitory Locations—A census operation where census workers conduct a 

personal interview with individuals who do not have a usual home elsewhere.

Field Verification—A census operation where census workers verify the existence of units that had 

been geocoded to a census block but did not match an address in the Master Address File.

Group Quarters Advance Visit—A census operation designed to inform the group quarters 

contact person of the upcoming enumeration.

Group Quarters Enumeration—A census operation designed to count people living or staying in 

places such as college residence halls, skilled-nursing facilities, group homes, military barracks, 

and correctional facilities. 

Group Quarters Validation—A census operation designed to determine the correct classification of 

addresses identified as “other living quarters” during the address canvassing operation. 

Mailout/Mailback—A census operation where most households in the United States will be mailed 

a census questionnaire by the U.S. Postal Service. Household respondents will be asked to fill out 

the questionnaires and mail them back to data capture centers.
C-8 Data Collection and Processing Procedures

U.S. Census Bureau, 2010 Census

Military Group Quarters Enumeration—A part of the Group Quarters Enumeration operation 

conducted on military bases and carried out in coordination with the military base point of 

contact to count military personnel. 

Military/Maritime Vessel Enumeration—A part of the Group Quarters operation conducted to 

enumerate persons on U.S. owned and operated flagged military and maritime vessels.

Nonresponse Follow-Up—A census operation where census workers visit housing units that did 

not return a completed questionnaire by mail to conduct a personal interview to obtain the 

required information. 

Nonresponse Follow-Up Reinterview—A quality check operation designed to ensure that the 

production enumerator followed field procedures and to identify enumerators who intentionally 

or unintentionally produced data errors so that work can be redone.

Questionnaire Assistance Center—A center established by a local census office to assist people 

with completing their questionnaires. The centers were established in community centers, large 

apartment buildings, childcare and educational centers, and so forth. The centers are staffed by 

volunteers and Census Bureau employees; also called walk-in questionnaire assistance centers.

Remote Alaska—A method of data collection used to enumerate the most sparsely settled, isolated 

parts of Alaska—areas accessible only by small plane, boat, snowmobile, 4-wheel-drive vehicle, 

dog sled, or a combination of these. 

Remote Update/Enumerate—A method of data collection conducted with a “team enumeration” 

method in sparsely inhabited areas of Maine and Alaska, where all enumeration is completed in 

just one visit.

Service-Based Enumeration—A group quarters operation designed to enumerate persons receiving 

services at shelters, soup kitchens, regularly scheduled mobile food vans, and those staying at 

preidentified nonsheltered outdoor locations. 

Telephone Questionnaire Assistance—A customer service operation assisting respondents who 

call in to inquire about census activities going on in their neighborhood or who want to obtain 

clarification to questions on the census questionnaire or who request to fill out the form through 

an interview over the phone. 

Update/Enumerate—A method of data collection conducted only in communities determined by 

local census officials where continually low response rates have been established from previous 

censuses or ongoing survey efforts, and mailing or hand-delivering forms is not cost beneficial. 

Enumeration is done by census takers who personally interview each household to collect 

information and update census address lists and maps at the same time. 

Update/Leave—A census operation where census workers update paper versions of census address 

lists and maps and leave questionnaires at housing units in mainly rural areas without street 

names and/or house numbers. Household respondents are expected to fill out the questionnaires 

and mail them to data capture centers.

Vacant Delete Check—A census operation where census workers visit addresses that workers 

recorded in Nonresponse Follow-Up as either vacant or not a housing unit on Census Day, April 1.
Data Collection and Processing Procedures C-9

U.S. Census Bureau, 2010 Census 

TIMELINE OF 2010 CENSUS OPERATIONS

Operation Conducted

Address Canvassing April 6, 2009–July 19, 2009

CCM Independent Listing Operation August 28, 2009–December 5, 2009

Group Quarters Validation September 28, 2009–October 23, 2009

Remote Alaska January 22, 2010–May 5, 2010

Group Quarters Advance Visit February 1, 2010–March 19, 2010

Telephone Questionnaire Assistance February 25, 2010–July 30, 2010

Questionnaire Assistance Centers February 26, 2010–April 19, 2010

Update/Leave March 1, 2010–April 2, 2010

CCM Initial Housing Unit Follow-Up March 4, 2010–April 23, 2010

Mailout/Mailback March 15, 2010–September 30, 2010

Be Counted Program March 19, 2010–April 19, 2010

Update/Enumerate March 22, 2010–May 29, 2010

Enumeration at Transitory Locations March 22, 2010–April 16, 2010

Remote Update Enumerate March 22, 2010–May 29, 2010

Service-Based Enumeration March 29, 2010–March 31, 2010

Military Group Quarters Enumeration March 30, 2010–May 14, 2010

Group Quarters Enumeration April 1, 2010–May 14, 2010

Military/Maritime Vessel Enumeration April 1, 2010–May 14, 2010

Second Questionnaire Mailing in 

Mailout/Mailback Areas 

(either targeted or blanket delivery) April 1, 2010–April 10, 2010

Coverage Follow-Up April 26, 2010–August 13, 2010

Nonresponse Follow-Up May 1, 2010–July 10, 2010

Nonresponse Follow-Up Reinterview May 7, 2010–July 17, 2010

Vacant Delete Check July 24, 2010–August 25, 2010

Field Verification August 6, 2010–September 3, 2010

CCM Person Interview August 14, 2010–October 2, 2010

CCM Person Follow-Up January 28, 2011–March 19, 2011

CCM Final Housing Unit Follow-Up May 5, 2011–June 15, 2011
C-10 Data Collection and Processing Procedures

U.S. Census Bureau, 2010 Census

LIST OF STATES’ SERVICES BY EACH REGIONAL OFFICE

Atlanta Alabama, Florida, Georgia

Boston Connecticut, Massachusetts, New Hampshire, New York (all counties except 

those covered by the New York regional office listed below), Rhode Island, Maine, 

Puerto Rico, Vermont, 

Charlotte Kentucky, North Carolina, South Carolina, Tennessee, Virginia

Chicago Illinois, Indiana, Wisconsin

Dallas Louisiana, Mississippi, Texas

Denver Arizona, Colorado, Montana, Nebraska, Nevada, New Mexico, North Dakota, 

South Dakota, Utah, Wyoming

Detroit Michigan, Ohio, West Virginia

Kansas City Arkansas, Iowa, Kansas, Minnesota, Missouri, Oklahoma

Los Angeles Hawaii, Southern California (counties of Fresno, Imperial, Inyo, Kern, Kings, Los 

Angeles, Madera, Mariposa, Merced, Monterey, Orange, Riverside, San Benito, San 

Bernardino, San Diego, San Luis Obispo, Santa Barbara, Tulare, and Ventura)

New York New Jersey (counties of Bergen, Essex, Hudson, Middlesex, Morris, Passaic, 

Somerset, Sussex, Union, and Warren), New York (counties of Bronx, Kings, Nassau, 

New York, Queens, Richmond, Rockland, Suffolk, and Westchester)

Philadelphia Delaware, District of Columbia, Maryland, New Jersey (all counties except 

those covered by the New York regional office listed above), Pennsylvania

Seattle Alaska, Idaho, Northern California (all counties except those covered by the Los 

Angeles regional office listed above), Oregon, Washington

<www.census.gov/regions>
Questionnaire D-1

U.S. Census Bureau, 2010 Census 

Appendix D.

Questionnaire
D-2 Questionnaire

U.S. Census Bureau, 2010 Census 
Questionnaire D-3

U.S. Census Bureau, 2010 Census 
D-4 Questionnaire

U.S. Census Bureau, 2010 Census 
Questionnaire D-5

U.S. Census Bureau, 2010 Census 
D-6 Questionnaire

U.S. Census Bureau, 2010 Census 
Maps 

U.S. Census Bureau, 2010 Census

Appendix E.

Maps

See the separate Population and Housing Unit Counts reports.

Operational Overview and Accuracy of the Data F-1

U.S. Census Bureau, 2010 Census

Appendix F.

Operational Overview and Accuracy of the Data

CONTENTS

Master Address File Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-1

Local Update of Census Addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-2

Address Canvassing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-2

Group Quarters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-2

Update/Leave. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-3

Nonresponse Follow-Up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-3

Other Address and Geocoding Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-3

Vacant/Delete Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-4

Field Verification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-4

Remote Areas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-5

Group Quarters Enumeration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-5

Service-Based Enumeration and Enumeration at Transitory Locations. . . . . . . . . . . . . . . . . . . . . . . F-5

Confidentiality of the Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-6

Title 13 U.S. Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-6

Disclosure Avoidance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-6

Data Swapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-6

Nonsampling Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-6

Types of Nonsampling Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-7

Reduction of Nonsampling Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-7

Resolving Multiple Responses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-8

Data Editing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-8

Count Imputation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-9

General Imputation Rules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F-9

MASTER ADDRESS FILE DEVELOPMENT

As in Census 2000, the base for the address list for the 2010 Census was the address list from the 

previous census. Various updates were made to the address list during the intervening decade. The 

primary source of new addresses after Census 2000 was the Delivery Sequence File (DSF) from the

U.S. Postal Service (USPS). The U.S. Census Bureau acquired this file of all mailing addresses in the United 

States and updated the Master Address File (MAF) twice a year (March and October) until February 2010. 

Addresses must be associated with a block to be included in the census. The process of associating these 

addresses with a block is called geocoding. For the Census Bureau, the file where geographic information 

is contained is the Topologically Integrated Geographic Encoding and Referencing System (TIGER®). During 

this decade, the MAF and TIGER® have been integrated into the MAF/TIGER® database (MTdb). 

For the processing of the DSF records, city-style addresses (containing a house number and street name) 

of residential units were applied to the MAF in those blocks that, in general terms, had been found to 

have a majority of city-style addresses in order that duplication would not result from the addition of 

these addresses. Another file from the USPS, the Locatable Address Conversion System (LACS), contained 

linkages for addresses that had been changed. Use of this file by the Census Bureau allowed for old 

and new addresses to be linked in the MTdb. This was especially desirable for linking the non-city-style 

addresses that had been converted to city-style addresses. 
F-2 Operational Overview and Accuracy of the Data

U.S. Census Bureau, 2010 Census

Various field operations, such as census tests and the update of rural area addresses for the American 

Community Survey, led to localized updates or updates in specific types of areas. In particular, updating 

addresses with post office box type addresses in the rural area was meant to balance the updating of the 

MTdb with city-style addresses from the DSF. 

Local Update of Census Addresses

The first large-scale update of addresses for the decennial census was the Local Update of Census 

Addresses (LUCA) program. In this program, governmental units (GUs) were allowed to participate in 

updating the address list in three different ways. One option allowed for review of the Census Bureau’s 

address list, while the other options allowed only for the GUs to submit a list of addresses to the Census 

Bureau. Under any of these options, new addresses submitted by the GUs were included on the subsequent 

address list. These addresses could be for housing units (HUs) or for group quarters (GQs). The submitted 

addresses were then included in the universe for validation in the next major address list development 

operation, Address Canvassing, which occurred between April and July 2009. 

Address Canvassing

Address Canvassing was conducted in all areas of the United States and Puerto Rico except in the areas 

that were designated for Remote Alaska or Remote Update Enumerate in the census. Address Canvassing 

was a dependent check of the list of addresses, as well as of the maps. The Address Canvassing operation 

was performed using automation, which allowed for the integration of address and map updates, as 

well as the imposition of rules on what constitutes a minimum allowable address and the collection of 

particular geographic fields. The allowable actions on the addresses in Address Canvassing were validate, 

nonresidential, delete, duplicate, address correction, and an action for designating possible GQs. Adds 

to the list were also allowed. All deletes and duplicates were validated during the next phase of the 

operation, called delete verification. The results from Address Canvassing were incorporated into the 

MTdb. One of the first uses of these results was for creating feedback to the GUs participating in LUCA. 

The results from processing the Address Canvassing updates were also used for the creation of the initial 

census address list starting in July 2009, the initial Universe Control and Management (UC&M) file. Printing 

of the questionnaires used this address list. 

Group Quarters

The results of Address Canvassing also contributed to the universe for the next operation, which was 

Group Quarters Validation (GQV). The procedures for creating the address list of GQs were significantly 

different for the 2010 Census as opposed to previous censuses. In order to reduce duplication and 

geographic data errors, the address lists of HUs and GQs were integrated in the MTdb. The list of potential 

GQs going into GQV was the accumulation of GQ addresses from Census 2000, GQ addresses acquired 

from various sources, and addresses listed as Other Living Quarters (potential GQs) in Address Canvassing. 

Cases designated as GQs through other sources were intended to be sent to GQV regardless of the Address 

Canvassing status. However, it was discovered during processing of the LUCA updates that GUs often 

listed apartment buildings or commercial units as GQs. The schedule for completing GQV, in October 2009, 

was one of the riskiest in the census. For these units to remain on the list of units to be checked in GQV 

put timely completion of the operation at risk, and thus, the entire census schedule. Therefore, from the 

LUCA updates making their way to GQV, only the units with facility names that included special key names 

known to be associated with group quarters were designated for follow-up in GQV unless they were also 

designated as possible GQs in Address Canvassing. The addresses in GQV could receive an action of GQ—

along with the type of GQ, HU, nonresidential, vacant, transient (meaning the location was connected to a 

geographic area that should be enumerated in the Enumeration at Transitory Locations operation), delete, 

or duplicate.

The results from GQV were processed in November 2009. Updates were made to the initial UC&M, 

resulting in the enumeration UC&M, or the full census universe. Units that were marked as housing units 
Operational Overview and Accuracy of the Data F-3

U.S. Census Bureau, 2010 Census

in GQV were designated as adds to the initial UC&M universe. Other adds to this universe resulted from 

DSF updates that had occurred between the creation of the Address List for Address Canvassing and the 

creation of the enumeration UC&M. There were three DSFs contributing new adds to this UC&M file. A 

supplemental printing of addressed questionnaires resulted from this updated file. These questionnaires 

were either added to the mail stream at the point that questionnaires were delivered by the USPS or sent to 

the Local Census Offices in those areas where the added addresses occurred in Update/Leave areas. 

Update/Leave

Update/Leave (U/L) is an operation in which questionnaires are hand-delivered due to potential 

problems with postal delivery of addresses. The presence of staff in the field for this delivery allows the 

simultaneous updating of the address lists and maps. Addresses on the address list in U/L areas received 

the actions of verify, correction, nonresidential, delete, or duplicate. Maps could also receive updates. The 

operation occurred between March 1 and April 2, 2010. There were approximately 12 million housing 

units in stateside U/L areas, and Puerto Rico (about 1.6 million addresses) was entirely U/L. There was no 

check on the deletes and duplicates designated in this operation because the operation was performed on 

paper and there was a timing issue with processing. The status of nonresponding units that were in the 

enumeration universe was checked in the later Nonresponse Follow-Up operation. 

Nonresponse Follow-Up

Nonresponse Follow-Up (NRFU) is the operation in which nonresponding households from both mailout/

mailback and U/L areas are followed up and enumerated, if possible. Other options within NRFU are to 

mark the unit vacant (either a regular vacant or seasonal), delete, or duplicate. It is also possible to add 

units and perform the enumeration on them. The maps also may be updated. The status of regular vacants 

and deletes is checked in the subsequent operation, the Vacant/Delete Check. 

Other Address and Geocoding Operations

No additional updates were made to the enumeration universe in the UC&M before the start of NRFU. 

However, there were still operations and processes adding addresses to the MTdb, or in some cases, 

adding geographic data that allowed the addresses to be included in the census. These were: 1) LUCA 

Appeals; 2) New Construction; 3) HU Address Review; 4) Count Review; 5) Spring 2010 DSF; 6) newly 

geocoded addresses; 7) addresses resulting from a follow-up of INFO-COMMs (standardized forms used to 

document problems, issues, and unusual situations or to ask questions about procedures and other workrelated matters by field staff) submitted during Address Canvassing; and 8) U/L added addresses. 

LUCA Appeals was a process where a GU that participated in LUCA submitted challenges to the outputs 

from Address Canvassing. The challenged addresses were reviewed, and those that were approved were 

accepted back onto the census list.

New Construction was an effort similar to LUCA in which the participating GU submitted addresses that 

represented newly constructed and livable housing.

The HU Address Review was a headquarters review of addresses coming from a variety of sources. In 

general, these were people who reported situations, such as large apartment buildings missing from the 

census universe, where the report made it to headquarters personnel. Staff in the Geography Division 

researched these address submissions to determine if they were truly missing from the census address list 

and, if so, why. When it was found that addresses should be included on the census address list and did 

not duplicate other addresses already on the census address list, they were submitted for processing in 

the same format as files from the New Construction and Count Review programs.

Count Review was another effort undertaken with governmental representatives with an eye toward 

identifying housing that was missing from the list.
F-4 Operational Overview and Accuracy of the Data

U.S. Census Bureau, 2010 Census

The Spring 2010 DSF contained mailable addresses as of February 2010. Residential addresses appearing 

on this list that were not already included in the MTdb were assumed to represent mostly newly 

constructed units. For the next source of addresses on this update, there were a few million addresses 

residing on the MTdb that had not yet been geocoded. It was assumed that these addresses would be 

added in Address Canvassing if they truly existed.

However, when Address Canvassing was completed and only about half of the addresses had been added 

in the operation, and at the same time there were some concerns about the coverage of the list, the 

Census Bureau undertook an independent effort in early 2010 to find geocodes for these units after first 

checking that the addresses were not represented on the list in another form.

The next addition of addresses resulted from Address Canvassing INFO-COMMs. The design of the 

automated instrument did not allow for units to be added during the Quality Control (QC) phase of the 

operation if the assignment had passed QC. Nevertheless, in some areas QC staff found large numbers 

of missing addresses that were not picked up within the QC sample. They filled out an INFO-COMM to 

apprise the local office staff of the situation. In early 2010, there was an effort to identify which of these 

cases were really missing units and where they should be added to the list. An input file that mimicked the 

inputs of the other operations adding addresses was created for these units to be added to the census list 

in this process, as well.

The final source of new addresses listed here was U/L adds. These are units that did not appear on the list 

used for U/L but that were identified as valid in the field. Questionnaires were delivered to these units, and 

updates were made to the MTdb based on the results of this operation. However, the processing of U/L 

actions could not be completed in time to update the NRFU universe without automation. Thus, in order 

to perform enumeration on U/L adds for households that did not return the form, the units needed to be 

included in the subsequent updated universe. 

Vacant/Delete Check

These addresses just described made it into the enumeration universe for the first time for the Vacant/

Delete Check (VDC). Not all of these addresses required a visit for enumeration during the VDC. In 

particular, if a householder at an address added during U/L mailed in the form in time, no additional visit 

was required. In addition, an operation dubbed the Late Add Mailing resulted in many of these addresses 

being mailed forms earlier than enumeration would have occurred. In particular, the LUCA Appeals 

addresses, the addresses from the most recent DSF that were geocoded to a block, and the addresses that 

were newly geocoded during the geocoding research were placed on a file for which questionnaires were 

printed and mailed. A unique processing ID was printed on each of these questionnaires, which enabled 

the questionnaires to be linked up to the census ID that was used when the units were added to the VDC 

universe. This also allowed for the information about receipt of a questionnaire to be passed back to the 

universe file and removed from the universe of follow-up cases. Therefore, the final list of units requiring 

follow-up and potential enumeration in VDC were the regular vacants and deletes as designated in NRFU 

and the new units added from the seven sources listed above for which no questionnaire was received 

by the time of universe creation. The universe of addresses printed within the address registers were all 

units that appeared in the enumeration universe plus the units added from the seven sources listed. One 

category of new address that did not appear on the VDC listing pages, due to timing, were the units that 

were added during NRFU. 

Field Verification

There was one final check of particular addresses in the field. This operation is called Field Verification, 

and it was performed in the 2010 Census much as it was in Census 2000. Only specific addresses within 

the entire universe of addresses were acted on during this status check. Units designated for follow-up in 

this operation received a status of valid (or verify), delete, or duplicate. The addresses in the universe for 

this check in the 2010 Census included two categories of cases. The first was a check of new addresses 

that resulted from Be Counted forms or calls to the Telephone Questionnaire Assistance line that did not 
Operational Overview and Accuracy of the Data F-5

U.S. Census Bureau, 2010 Census

have a related census ID. These addresses needed to be verified in the field before they were added to 

the census. They must be associated with a particular block before they could be sent for field work. The 

second category of cases was units that potentially needed to be removed from the universe based on 

the identification of duplicated persons in those units. Person duplication occurs for many reasons, one of 

which is duplication of housing units on the address list. Units linked by person matching that are within 

a close geographic area have been found in testing to be highly associated with housing-level problems. 

However, there are other situations that can lead to such person duplication that are not housing unit 

duplication, so these units identified as potential duplicates needed to be field checked before they could 

be safely removed from the census address list. For those units that were designated as duplicates, an 

indicator of which unit on the list that unit duplicated was collected.

Remote Areas

The descriptions above cover the vast majority of housing units in the United States and in all of Puerto 

Rico. However, there are some particularly remote or problematic areas that were designated for other 

types of enumeration. The first of these to start was Remote Alaska. In this operation, enumeration was 

scheduled to occur in fishing and hunting villages before the ice broke and the villagers scattered from 

their winter homes. Other areas in Alaska that were remote but where the population is stationary were 

designated for Remote Update/Enumerate. The methodology is the same for these two operations. The 

incoming address list was based on what was there during Census 2000. Updates were made to the 

address list and maps, and the households were enumerated at the same time. An area of Maine was also 

designated for Remote Update/Enumerate. 

Some areas of the country (covering about 1.5 million addresses) were designated for Update/Enumerate. 

In these areas, Address Canvassing was completed, but it was felt that enumeration by Mailout/Mailback 

or U/L would have been problematic. These areas could be seasonal housing, federally designated tribal 

areas, or areas with particularly low predicted response rates based on various demographic factors. 

In Update/Enumerate, as in Remote Update/Enumerate and Remote Alaska, updates were made to the 

address list and maps at the same time that enumeration was completed. In general, this is the last 

operation that occurs in these areas, although it is possible for units in the Field Verification universe to be 

in these areas. 

GROUP QUARTERS ENUMERATION

A list of nonstandard housing, such as college dormitories and group homes, was tracked in the MTdb in 

conjunction with the housing unit list. The list of these GQs was compiled from various sources, including 

the Census 2000 list of GQs, LUCA participants, the Federal-State Cooperative for Population Estimates, 

and Address Canvassing. The GQV of these addresses occurred in October 2009, as described above. 

The units that remained GQs after this check were included in Group Quarters Advance Visit (GQAV), and 

then Group Quarters Enumeration (GQE). In GQE, individual census questionnaires—meaning individual 

questionnaires for each person—were distributed at the GQs and collected by the field staff. A count of 

persons associated with a particular GQ resulted from this operation. 

SERVICE-BASED ENUMERATION AND ENUMERATION AT TRANSITORY LOCATIONS

Service-Based Enumeration (SBE) was designed to account for the enumeration of persons without a usual 

residence that use service facilities (i.e., shelters, soup kitchens, and mobile food vans). In the

2010 Census, 3 days (March 29–31) were designated for these enumeration activities. Different types of 

facilities were designated for different days. Only persons using the service facility on the interview day 

were enumerated at that location. It was possible for people to be counted in more than one location due 

to use of different facilities on subsequent days. There is an unduplication of SBE persons for the purpose 

of minimizing this duplication. 
F-6 Operational Overview and Accuracy of the Data

U.S. Census Bureau, 2010 Census

People experiencing homelessness could also complete a Be Counted form and check the box indicating 

this status. To the extent that such persons could be associated with a state and county based on the 

information provided on the form, they will be counted at a Group Quarters within that state and county. 

Certain areas were designated for Enumeration at Transitory Locations (ETL). These included RV parks 

and marinas where people were living as of Census Day if people living in these locations had no other 

permanent place to stay. The locations where ETL took place were designated in GQAV. When people were 

enumerated in ETL, the particular location was considered a housing unit. 

CONFIDENTIALITY OF THE DATA

The Census Bureau has modified some data in this data release to protect confidentiality. Title 13 U.S. 

Code, Section 9, prohibits the Census Bureau from publishing results in which an individual’s data can be 

identified.

The Census Bureau’s internal Disclosure Review Board monitors the disclosure review process and sets the 

confidentiality rules for all data releases. A checklist approach is used to ensure that all potential risks are 

considered and addressed. A list of possible concerns is created and the Disclosure Review Board makes 

sure that the appropriate steps are taken to assure the confidentiality of the data. 

Title 13 U.S. Code

Title 13 of the U.S. Code authorizes the Census Bureau to conduct surveys and censuses and mandates 

that any information obtained from private individuals and establishments remains confidential. Section 

9 of Title 13 prohibits the Census Bureau from releasing “any publication whereby the data furnished 

by any particular establishment or individual under this title can be identified.” Section 214 of Title 13, 

as modified by the Federal Sentencing Reform Act, imposes a fine of not more than $250,000 and/or 

imprisonment of not more than 5 years for publication or communication in violation of Section 9.

Disclosure Avoidance

Disclosure avoidance is the process of disguising data to protect confidentiality. A disclosure of data 

occurs when someone can use published statistical information to identify an individual who provided 

information under a pledge of confidentiality. Using disclosure avoidance, the Census Bureau modifies or 

removes all of the characteristics that put confidential information at risk for disclosure. Although it may 

appear that a table shows information about a specific individual, the Census Bureau has taken steps (such 

as data swapping) to disguise the original data while making sure the results are useful.

Data Swapping

Data swapping is a method of disclosure avoidance designed to protect confidentiality in tables of frequency 

data (the number or percentage of the population with certain characteristics). Data swapping is done by 

editing the source data or exchanging records for a sample of cases. A sample of households is selected and 

matched on a set of selected key variables with households in neighboring geographic areas (geographic 

areas with a small population) that have similar characteristics (same number of adults, same number of 

children, etc.). Because the swap often occurs within a geographic area with a small population, there is no 

effect on the marginal totals for the geographic area with a small population or for totals that include data 

from multiple geographic areas with small populations. Because of data swapping, users should not assume 

that tables with cells having a value of one or two reveal information about specific individuals.

NONSAMPLING ERROR

In any large-scale statistical operation, such as the 2010 Census, human- and computer-related errors 

occur. These errors are commonly referred to as nonsampling errors. Such errors include not enumerating 

every household or every person in the population, not obtaining all required information from the 

respondents, obtaining incorrect or inconsistent information, and recording information incorrectly. In 
Operational Overview and Accuracy of the Data F-7

U.S. Census Bureau, 2010 Census

addition, errors can occur during the field review of the enumerators’ work, during clerical handling of the 

census questionnaires, or during the electronic processing of the questionnaires.

While it is impossible to completely eliminate nonsampling error from an operation as large and complex 

as the decennial census, the Census Bureau attempts to control the sources of such error during the 

collection and processing operations. Described below are the primary sources of nonsampling error and 

the programs instituted to control this error in the 2010 Census. The success of these programs, however, 

was contingent upon how well the instructions actually were carried out during the census. 

Types of Nonsampling Error

Nonresponse

Nonresponse to particular questions on the census questionnaire or the failure to obtain any information 

for a housing unit allows for the introduction of bias into the data because the characteristics of the 

nonrespondents have not been observed and may differ from those reported by respondents. As a result, 

any imputation procedure using respondent data may not completely reflect these differences either at 

the elemental level (individual person or housing unit) or on the average. Some protection against the 

introduction of large biases is afforded by minimizing nonresponse. Characteristics for the nonresponses 

were imputed by using reported data for a person or housing unit with similar characteristics.

Respondent and Enumerator Error

The person answering the mail questionnaire for a household or responding to the questions posed by 

an enumerator could serve as a source of error, although the question wording was extensively tested in 

several experimental studies prior to the census. The mail respondent may overlook or misunderstand a 

question or answer a question in a way that cannot be interpreted correctly by the data capture system. 

The enumerator may also misinterpret or otherwise incorrectly record information given by a respondent 

or may fail to collect some of the information for a person or household. To control problems such as 

these with the field enumeration, the work of enumerators was monitored carefully. Field staff were 

prepared for their tasks by using standardized training packages that included hands-on experience in 

using census materials. A sample of the households interviewed by each enumerator were reinterviewed 

to control for the possibility of fabricated data being submitted by enumerators.

Processing Error

The many phases involved in processing the census data represent potential sources for the introduction 

of nonsampling error. The processing of the census questionnaires completed by enumerators included 

field review by the crew leader, check-in, and transmittal of completed questionnaires. No field reviews 

were done on the mail return questionnaires for this census.

Error may also be introduced by the misinterpretation of data by the data capture system or the failure to 

capture all the information that the respondents or enumerators provided on the forms. Write-in entries 

go through coding operations, which may also be a source of processing error in the data. Many of the 

various field, coding, and computer operations undergo a number of quality control checks to help ensure 

their accurate application.

Reduction of Nonsampling Error

To reduce various types of nonsampling errors, a number of techniques were implemented during the 

planning, development of the mailing address list, data collection, and data processing activities. Quality 

assurance methods were used throughout the data collection and processing phases of the census to 

improve the quality of the data. A reinterview program was implemented to minimize the errors in the data 

collection phase for enumerator-filled questionnaires.
F-8 Operational Overview and Accuracy of the Data

U.S. Census Bureau, 2010 Census

Several coverage improvement programs were implemented during the development of the census address 

list and census enumeration and processing to minimize undercoverage of the population and housing 

units. These programs were developed based on experience from previous decennial censuses and results 

from the 2010 Census testing cycle. 

•	 Be Counted questionnaires, unaddressed forms requesting all questionnaire items plus a few additional

items, were available in public locations for people who believed they were not otherwise counted.

• 	An introductory letter was sent to all mailout/mailback addresses and many addresses in update/leave

areas prior to the mailing of the census form. A reminder postcard was also sent to these addresses.

• 	A replacement questionnaire was sent to nonresponding addresses in selected areas.

• 	Bilingual English/Spanish questionnaires were sent to all addresses in selected areas.

•	 Forms in Spanish, Chinese (simplified), Korean, Russian, and Vietnamese were mailed to those who

requested them and Language Assistance Guides were available in 59 languages.

•	 A well-publicized toll-free phone number was available to answer questions about the forms, and

responses could be taken over the phone.

•	 Under the LUCA program, local officials had the opportunity to address specific concerns about the

accuracy and completeness of the address list.

•	 A Coverage Followup (CFU) telephone interview operation was implemented with the express purpose

of improving within household coverage. Cases were telephoned when there was a discrepancy 

between the number in the count of persons box and the number of persons with data. A householdlevel undercoverage question was added to the questionnaire, and person-level overcoverage questions 

were also added. Certain categories of households checking these boxes were also selected for CFU 

for roster clarification. In addition, large households, or those with more than six household members, 

were selected for inclusion in CFU for the purpose of collecting full demographic data for persons 

beyond the first six. 

Resolving Multiple Responses

With multiple ways for people to initiate or complete their enumeration, as well as the field follow-up 

operations, it was very likely that some households would be enumerated more than once. A special 

computer process was implemented to control the extent of this type of nonsampling error by resolving 

situations where more than one form was received from an address. The process consisted of several 

steps. Addresses that had more than one viable return were analyzed. Household data from one form 

were chosen as the household data to use in subsequent census processing. There are situations in which 

persons can then be added to the household roster if they are not already represented there. These are the 

cases in which a Be Counted form for a partial household was submitted for the same address, and when 

an enumeration operation discovers a person who should be counted at a different address (a Usual Home 

Elsewhere) from the address being enumerated. 

DATA EDITING 

The objective of the processing operation was to produce a set of data that describes the population as 

accurately and clearly as possible. As with Census 2000, information on 2010 Census questionnaires 

generally was not edited for consistency, completeness, and acceptability during field data collection

nor during data capture operations. Enumerator-filled questionnaires were reviewed by census crew 

leaders and local office clerks for adherence to specified procedures. No clerical review of mail return 

questionnaires was done to ensure that the information on the form could be data captured, nor were 

households contacted to collect data that were missing from census returns as in previous censuses. 
Operational Overview and Accuracy of the Data F-9

U.S. Census Bureau, 2010 Census

Most census questionnaires received by mail from respondents as well as those filled by enumerators were 

processed through a new contractor-built image scanning system that used optical mark and character 

recognition to convert the responses into computer files. The optical character recognition, or OCR, process 

used several pattern and context checks to estimate accuracy thresholds for each write-in field. The system 

also used edits on interpreted write-in responses to decide whether the field values read by the machine 

interpretation were acceptable. If the value read had a lower than acceptable accuracy threshold or was 

outside of the edit range, the image of the item was displayed to a keyer, who then entered the response.

To control the creation of possibly erroneous persons from questionnaires completed incorrectly or 

containing stray marks, an edit on the number of persons indicated on each mail return and enumeratorfilled questionnaire was implemented as part of the data capture system. In addition, a new edit identified 

questionnaires with information written outside of the response boxes. Detection of either of these 

conditions by the edits subsystem resulted in the review of the questionnaire image at a workstation by an 

operator who ensured that the person data were captured fully and correctly. 

At Census Bureau headquarters, the data records were subjected to a computer edit that identified 

households exhibiting a possible coverage problem and those with more than six household members. 

Attempts were made to contact these households on the telephone to correct the count inconsistency and 

to collect the census data for those people for whom there was no room on the questionnaire.

Count Imputation 

Once census processing is completed, each address included in the census data collection has to be 

classified as a nonexistent unit, a vacant unit, or an occupied housing unit. Records that are classified 

as an occupied unit also need a reported number of residents. This information is necessary to have a 

complete count of the population and housing units in the United States as of Census Day. Because of the 

complexity of census operations, there are records that do not have such information by the end of the 

follow-up activities and data processing. To fill in this missing information, the Census Bureau conducted 

count imputation, which assigns a unit status and household size to records without such information. 

This process also included assigning household size to occupied units without household size information. 

Count imputation processing did not include group quarters.

In count imputation, all the records in the enumeration universe were partitioned within a designated 

geographical area into small groups based on certain characteristics. For each small group, a probability 

distribution of unit status and size from the records that had this information was created. Then, the 

distribution was used to impute for the missing data status and/or household size.

General Imputation Rules

The final automated edit and imputation processes determined the final values of questionnaire data items 

for records with missing or invalid values in collected data. Imputations, which were needed most often 

when an entry for a given item was missing, included three general procedures known as assignments, 

allocations, and substitution. Assignments and allocations were imputations of characteristic items on an 

item-by-item basis, whereas the substitution process imputed data for up to six persons in a household 

at one time. Each of these procedures ensured the completeness and consistency of the data by providing 

acceptable codes for missing or unacceptable entries.

The first step in the edit process was to assign acceptable codes in place of unacceptable entries or blanks 

when acceptable data were found for that same person. When one characteristic item reported for a person 

was inconsistent with other information provided for that same person, acceptable codes or values that 

were consistent with one item of reported information were assigned. The edit procedures also assigned 

race or Hispanic origin from a matched person record in Census 2000 or in the American Community 

Survey (2000–2009) when these fields were missing. These assignment steps strove to ensure consistency 

across characteristic data.
F-10 Operational Overview and Accuracy of the Data

U.S. Census Bureau, 2010 Census

The next step in the edit process, known as allocation, was to impute responses for missing person 

or housing-unit characteristic data. The general procedure for changing unacceptable entries through 

allocation was to derive an entry for a person (or housing unit) that was consistent with entries for another 

person (or housing unit) with similar characteristics. Allocation rates for census items were made available 

with the published census data.

Another way corrections are made during the edit and imputation process was through substitution; that 

is, the replication of a full set of characteristics for people in a household. When there was an indication 

that a household was occupied by a specified number of people but the questionnaire record contained no 

information for the people within the household or the occupants were not listed on the questionnaire, a 

previously accepted household of the same size was selected as a substitute. The full set of characteristics 

of the substitute was duplicated. Counts of substituted persons and the occupied housing units containing 

substituted persons were made available with the published census data.
Residence Rule & Residence Situations for the 2010 Census of the United States G-1

U.S. Census Bureau, 2010 Census

Appendix G.

Residence Rule and Residence Situations for the

2010 Census of the United States

CONTENTS

Where You Are Counted Is Important. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

The Concept of Usual Residence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

The Residence Rule. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-2

People Away From Their Usual Residence on Census Day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-2

Visitors on Census Day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-2

People Who Live in More Than One Place. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-2

People Without a Usual Residence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-3

Students. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-3

Movers on Census Day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-3

People Who Are Born or Die on Census Day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-3

Nonrelatives of the Householder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-4

U.S. Military Personnel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-4

Merchant Marine Personnel on U.S. Flag Maritime/Merchant Vessels. . . . . . . . . . . . . . . . . . . . . . . . G-4

Foreign Citizens in the United States. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-4

U.S. Citizens and Their Dependents Living Outside the United States. . . . . . . . . . . . . . . . . . . . . . . G-5

People in Correctional Facilities for Adults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-5

People in Group Homes and Residential Treatment Centers for Adults. . . . . . . . . . . . . . . . . . . . . . . G-5

People in Health Care Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-5

People in Juvenile Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-6

People in Residential School-Related Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-6

People in Shelters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-6

People in Transitory Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-6

People in Religious-Related Residential Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-6

People in Workers’ Residential Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-6

WHERE YOU ARE COUNTED IS IMPORTANT

For the 2010 Census, the U.S. Census Bureau is committed to counting every person. Just as important, 

however, is the Census Bureau’s commitment to counting every person in the correct place. The 

fundamental reason the decennial census is conducted is to fulfill the constitutional requirement

(Article I, Section 2) to apportion the seats in the U.S. House of Representatives among the states. Thus,

for a fair and equitable apportionment, it is crucial that people are counted in the right place during the

2010 Census. 

THE CONCEPT OF USUAL RESIDENCE

Planners of the first U.S. decennial census in 1790 established the concept of “usual residence” as the 

main principle in determining where people were to be counted. This concept has been followed in all 

subsequent censuses and is the guiding principle for the 2010 Census. Usual residence is defined as the 

place where a person lives and sleeps most of the time. This place is not necessarily the same as the 

person’s voting residence or legal residence. 
G-2 Residence Rule & Residence Situations for the 2010 Census of the United States

U.S. Census Bureau, 2010 Census

Determining usual residence is easy for most people. Given our nation’s wide diversity in types of living 

arrangements, however, the usual residence for some people is not as apparent. A few examples are 

people experiencing homelessness, snowbirds, children in shared custody arrangements, college students, 

live-in employees, military personnel, and people who live in workers’ dormitories. 

Applying the usual residence concept to real living situations means that people will not always be 

counted at the place where they happen to be staying on Thursday, April 1, 2010 (Census Day). For 

example, people who are away from their usual residence while on vacation or on a business trip on 

Census Day should be counted at their usual residence. People who live at more than one residence during 

the week, month, or year should be counted at the place where they live most of the time. People without 

a usual residence, however, should be counted where they are staying on Census Day. 

THE RESIDENCE RULE

The residence rule is used to determine where people should be counted in the United States during the 

2010 Census. The rule says:

Count people at their usual residence, which is the place where they live and sleep most of the time. 

People in certain types of facilities or shelters (i.e., places where groups of people live together) on 

Census Day should be counted at the facility or shelter. 

People who do not have a usual residence, or cannot determine a usual residence, should be counted 

where they are on Census Day.

This residence rule also is used to determine where people are counted in the 2010 Census of Puerto Rico.

The following sections describe how the residence rule applies for people in various living situations. 

PEOPLE AWAY FROM THEIR USUAL RESIDENCE ON CENSUS DAY

People away from their usual residence on Thursday, April 1, 2010 (Census Day), such as on a vacation 

or a business trip, visiting, traveling outside the United States, or working elsewhere without a usual 

residence there (for example, as a truck driver or traveling salesperson)—Counted at the residence where 

they live and sleep most of the time.

VISITORS ON CENSUS DAY

Visitors on Thursday, April 1, 2010 (Census Day) who will return to their usual residence—Counted at the 

residence where they live and sleep most of the time.

Citizens of foreign countries who are visiting the United States on Thursday, April 1, 2010 (Census Day), 

such as on a vacation or a business trip—Not counted in the census.

PEOPLE WHO LIVE IN MORE THAN ONE PLACE

People living away most of the time while working, such as people who live at a residence close to where 

they work and return regularly to another residence—Counted at the residence where they live and sleep 

most of the time. If there is no residence where they live and sleep most of the time, they are counted 

where they live and sleep more than anywhere else. If time is equally divided, or if usual residence cannot 

be determined, they are counted at the residence where they are staying on Thursday, April 1, 2010 

(Census Day).

People who live at two or more residences (during the week, month, or year), such as people who travel 

seasonally between residences (for example, snowbirds)—Counted at the residence where they live 

and sleep most of the time. If there is no residence where they live and sleep most of the time, they 

are counted where they live and sleep more than anywhere else. If time is equally divided, or if usual 

residence cannot be determined, they are counted at the residence where they are staying on Thursday, 

April 1, 2010 (Census Day).
Residence Rule & Residence Situations for the 2010 Census of the United States G-3

U.S. Census Bureau, 2010 Census

Children in shared custody or other arrangements who live at more than one residence—Counted at the 

residence where they live and sleep most of the time. If time is equally divided, they are counted at the 

residence where they are staying on Thursday, April 1, 2010 (Census Day).

PEOPLE WITHOUT A USUAL RESIDENCE 

People who cannot determine a usual residence—Counted where they are staying on Thursday, April 1, 

2010 (Census Day).

People at soup kitchens and regularly scheduled mobile food vans—Counted at the residence where they 

live and sleep most of the time. If they do not have a place they live and sleep most of the time, they 

are counted at the soup kitchen or mobile food van location where they are on Thursday, April 1, 2010 

(Census Day).

People at targeted non-sheltered outdoor locations—Counted at the outdoor location where people 

experiencing homelessness stay without paying.

STUDENTS

Boarding school students living away from their parental home while attending boarding school below the 

college level, including Bureau of Indian Affairs boarding schools—Counted at their parental home rather 

than at the boarding school.

College students living at their parental home while attending college—Counted at their parental home.

College students living away from their parental home while attending college in the United States (living 

either on-campus or off-campus)—Counted at the on-campus or off-campus residence where they live and 

sleep most of the time.

College students living away from their parental home while attending college in the United States (living 

either on-campus or off-campus) but staying at their parental home while on break or vacation—Counted 

at the on-campus or off-campus residence where they live and sleep most of the time.

U.S. college students living outside the United States while attending college outside the United States—Not 

counted in the census.

Foreign students living in the United States while attending college in the United States (living either 

on-campus or off-campus)—Counted at the on-campus or off-campus residence where they live and sleep 

most of the time.

MOVERS ON CENSUS DAY 

People who move into a residence on Thursday, April 1, 2010 (Census Day) who have not been listed on a 

questionnaire for any residence—Counted at the residence they move into on Census Day.

People who move out of a residence on Thursday, April 1, 2010 (Census Day) and have not moved into a 

new residence on Thursday, April 1, 2010 (Census Day) and who have not been listed on a questionnaire 

for any residence—Counted at the residence from which they moved.

People who move out of a residence or move into a residence on Thursday, April 1, 2010 (Census Day) who 

have already been listed on a questionnaire for any residence—If they have already been listed on one 

questionnaire, do not list them on any other questionnaire.

PEOPLE WHO ARE BORN OR DIE ON CENSUS DAY

Babies born on or before 11:59:59 p.m. on Thursday, April 1, 2010 (Census Day)—Counted at the 

residence where they will live and sleep most of the time, even if they are still in the hospital on April 1, 

2010 (Census Day).

Babies born after 11:59:59 p.m. on Thursday, April 1, 2010 (Census Day)—Not counted in the census.
G-4 Residence Rule & Residence Situations for the 2010 Census of the United States

U.S. Census Bureau, 2010 Census

People who die before Thursday, April 1, 2010 (Census Day)—Not counted in the census.

People who die on Thursday, April 1, 2010 (Census Day)—Counted in the census if they are alive at any 

time on April 1, 2010. 

NONRELATIVES OF THE HOUSEHOLDER

Roomers or boarders—Counted at the residence where they live and sleep most of the time.

Housemates or roommates—Counted at the residence where they live and sleep most of the time.

Unmarried partners—Counted at the residence where they live and sleep most of the time.

Foster children or foster adults—Counted at the residence where they live and sleep most of the time.

Live-in employees, such as caregivers or domestic workers—Counted at the residence where they live and 

sleep most of the time. 

U.S. MILITARY PERSONNEL 

U.S. military personnel living in military barracks in the United States—Counted at the military barracks.

U.S. military personnel living in the United States (living either on base or off base) but not in barracks—

Counted at the residence where they live and sleep most of the time.

U.S. military personnel on U.S. military vessels with a U.S. homeport—Counted at the onshore U.S. 

residence where they live and sleep most of the time. If they have no onshore U.S. residence, they are 

counted at their vessel’s homeport. 

People in military disciplinary barracks and jails in the United States—Counted at the facility.

People in military treatment facilities with assigned active duty patients in the United States—Counted at 

the facility if they are assigned there.

U.S. military personnel living on or off a military installation outside the United States, including 

dependents living with them—Counted as part of the U.S. overseas population. They should not be 

included on any U.S. census questionnaire.

U.S. military personnel on U.S. military vessels with a homeport outside the United States—Counted as part 

of the U.S. overseas population. They should not be included on any U.S. census questionnaire.

MERCHANT MARINE PERSONNEL ON U.S. FLAG MARITIME/MERCHANT VESSELS

Crews of U.S. flag maritime/merchant vessels docked in a U.S. port or sailing from one U.S. port to another 

U.S. port on Thursday, April 1, 2010 (Census Day)—Counted at the onshore U.S. residence where they live 

and sleep most of the time. If they have no onshore U.S. residence, they are counted at their vessel. If the 

vessel is docked in a U.S. port, crewmembers with no onshore U.S. residence are counted at the port. If the 

vessel is sailing from one U.S. port to another U.S. port, crewmembers with no onshore U.S. residence are 

counted at the port of departure.

Crews of U.S. flag maritime/merchant vessels engaged in U.S. inland waterway transportation on 

Thursday, April 1, 2010 (Census Day)—Counted at the onshore residence where they live and sleep most 

of the time.

Crews of U.S. flag maritime/merchant vessels docked in a foreign port, sailing from one foreign port to 

another foreign port, sailing from a U.S. port to a foreign port, or sailing from a foreign port to a U.S. port 

on Thursday, April 1, 2010 (Census Day)—Not counted in the census. 

FOREIGN CITIZENS IN THE UNITED STATES

Citizens of foreign countries living in the United States—Counted at the U.S. residence where they live and 

sleep most of the time.
Residence Rule & Residence Situations for the 2010 Census of the United States G-5

U.S. Census Bureau, 2010 Census

Citizens of foreign countries living in the United States who are members of the diplomatic community—

Counted at the embassy, consulate, United Nations’ facility, or other residences where diplomats live.

Citizens of foreign countries visiting the United States, such as on a vacation or business trip—Not counted 

in the census. 

U.S. CITIZENS AND THEIR DEPENDENTS LIVING OUTSIDE THE UNITED STATES

U.S. citizens living outside the United States who are employed as civilians by the U.S. government, 

including dependents living with them—Counted as part of the U.S. overseas population. They should not 

be included on any U.S. census questionnaire.

U.S. citizens living outside the United States who are not employed by the U.S. government, including 

dependents living with them—Not counted in the census.

U.S. military personnel living on or off a military installation outside the United States, including 

dependents living with them—Counted as part of the U.S. overseas population. They should not be 

included on any U.S. census questionnaire.

U.S. military personnel on U.S. military vessels with a homeport outside the United States—Counted as part 

of the U.S. overseas population. They should not be included on any U.S. census questionnaire.

PEOPLE IN CORRECTIONAL FACILITIES FOR ADULTS

People in correctional residential facilities on Thursday, April 1, 2010 (Census Day)—Counted at the facility.

People in federal detention centers on Thursday, April 1, 2010 (Census Day)—Counted at the facility.

People in federal and state prisons on Thursday, April 1, 2010 (Census Day)—Counted at the facility.

People in local jails and other municipal confinement facilities on Thursday, April 1, 2010 (Census Day)—

Counted at the facility.

PEOPLE IN GROUP HOMES AND RESIDENTIAL TREATMENT CENTERS FOR ADULTS

People in group homes intended for adults (non-correctional)—Counted at the facility.

People in residential treatment centers for adults (non-correctional)—Counted at the residence where they 

live and sleep most of the time. If they do not have a residence where they live and sleep most of the time, 

they are counted at the facility.

PEOPLE IN HEALTH CARE FACILITIES

Patients in general or Veterans Affairs hospitals (except psychiatric units) on Thursday, April 1, 2010 

(Census Day), including newborn babies still in the hospital on Census Day—Counted at the residence 

where they live and sleep most of the time. Newborn babies should be counted at the residence where 

they will live and sleep most of the time.

People in hospitals on Thursday, April 1, 2010 (Census Day) who have no usual home elsewhere—Counted 

at the facility.

People staying in in-patient hospice facilities on Thursday, April 1, 2010 (Census Day)—Counted at the 

residence where they live and sleep most of the time. If they do not have a residence where they live and 

sleep most of the time, they are counted at the facility. 

People in mental (psychiatric) hospitals and psychiatric units for long-term non-acute care in other 

hospitals on Thursday, April 1, 2010 (Census Day)—Counted at the facility.

People in nursing facilities/skilled nursing facilities on Thursday, April 1, 2010 (Census Day)—Counted at 

the facility. 
G-6 Residence Rule & Residence Situations for the 2010 Census of the United States

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PEOPLE IN JUVENILE FACILITIES

People in correctional facilities intended for juveniles on Thursday, April 1, 2010 (Census Day)—Counted at 

the facility.

People in group homes for juveniles (non-correctional) on Thursday, April 1, 2010 (Census Day)—Counted 

at the facility.

People in residential treatment centers for juveniles (non-correctional) on Thursday, April 1, 2010 (Census 

Day)—Counted at the facility. 

PEOPLE IN RESIDENTIAL SCHOOL-RELATED FACILITIES

People in college/university student housing—Counted at the college/university student housing.

Boarding school students living away from their parental home while attending boarding school below the 

college level, including Bureau of Indian Affairs boarding schools—Counted at their parental home rather 

than at the boarding school.

People in residential schools for people with disabilities on Thursday, April 1, 2010 (Census Day)—Counted 

at the school. 

PEOPLE IN SHELTERS

People in emergency and transitional shelters (with sleeping facilities) on Thursday, April 1, 2010 (Census 

Day) for people experiencing homelessness—Counted at the shelter.

People in living quarters for victims of natural disasters—Counted at the residence where they live and 

sleep most of the time. If they do not have a residence where they live and sleep most of the time, they are 

counted at the facility.

People in domestic violence shelters on Thursday, April 1, 2010 (Census Day)—Counted at the shelter. 

PEOPLE IN TRANSITORY LOCATIONS

People at transitory locations, such as recreational vehicle (RV) parks, campgrounds, hotels and motels 

(including those on military sites), hostels, marinas, racetracks, circuses, or carnivals—Counted at the 

residence where they live and sleep most of the time. If there is no residence where they live and sleep 

most of the time, they are counted where they live and sleep more than anywhere else. If time is equally 

divided, or if usual residence cannot be determined, they are counted at the place where they are staying 

on Thursday, April 1, 2010 (Census Day). 

PEOPLE IN RELIGIOUS-RELATED RESIDENTIAL FACILITIES

People in religious group quarters, such as convents and monasteries—Counted at the residence where 

they live and sleep most of the time. If they do not have a residence where they live and sleep most of the 

time, they are counted at the facility.

PEOPLE IN WORKERS’ RESIDENTIAL FACILITIES

People in workers’ group living quarters and Job Corps Centers—Counted at the residence where they live 

and sleep most of the time. If they do not have a residence where they live and sleep most of the time, 

they are counted at the facility.
Acknowledgments H-1

U.S. Census Bureau, 2010 Census

Appendix H.

Acknowledgments

The Administrative and Customer Services Division, Francis Grailand Hall, Division Chief; Claudette E. 

Bennett, Assistant Division Chief for Product Development and Publications Services; Corey Beasley, 

Section Chief for Graphic Design; Janet Sweeney, Section Chief for Editorial Services. Other Contributors: 

Christine E. Geter, Elzie Golden, Steven McIntyre, Amanda J. Perry, Vikki Porter, Daphanie M. 

Smallwood.

The Data Access and Dissemination Systems Office, Jeffrey D. Sisson, Program Manager; Marian E. 

Brady, Implementation Manager; Deidre C. Hicks, Business Manager. Team Leads: Rosalie A. Britt, 

Margaret G. Baker, Robert D. Chestnut, Richard C. Hulkenberg II. Other Contributors: Amy M. 

Bishton, Brandi R. Brehon, John K. Butler Jr., Brenda Compton, Jack F. Davis, Raymond W. Davis, 

Kimberly M. DePhillip, Janis A. Ennis, Sharon M. Gross, Sharon K. Fortuna, Beverly B. Fransen, 

Jean M. Haynes, Jeremy Melissari, Jaclina J. Mommsen, Mike A. Pasztor, Patricia Thompson, 

Daniel Wellwood, Berlyn A. Wheeler.

The Geography Division, Timothy Trainor, Division Chief; Atri Kalluri, Assistant Division Chief 

for Spatial Data Systems and Database Management; Michael Ratcliffe, Assistant Division Chief for 

Geocartographic Products and Criteria. Primary contributors: Elise Alkire, Angela Andrade, Dierdre 

Attardi, Constance Beard, Michael DeGennaro, Amy Fischer, Michael Fournier, Jennifer Holland, 

Noelle Joll, Stephen Jones, Ryan Kenma, Douglas Lockhart, Joe Marinucci, Suzanne McArdle, 

Andrew McIntire, Sara Mishler, Amanda Moritz, Jessica Namie, Linda Orsini, Vince Osier, Nick 

Padfield, Timothy Puzycki, Ricardo Ruiz, Matthew Schell, Meghan Smith, Stephanie Spahlinger, 

Jay Spurlin, William Thompson, Scott Wilcox. Other Contributors: Shonin Anacker, April Avnayim, 

Yvonne Bahn, Paul Donlin, Kevin Hawley, Cheryl Hayes, Colleen Joyce, Alan Longshore, Joan 

Meiller, Kimberly Newkirk, Priscilla O’Donnell, Radhika Pullangari, Lourdes Ramirez, David 

Tarr, Laura Waggoner, Gregory Yapundich.

The Population Division, Enrique J. Lamas, Division Chief; James Fitzsimmons, Assistant Division 

Chief for Geographic Studies and Information Resources; Karen Humes, Assistant Division Chief for 

Special Population Statistics; Louisa F. Miller, Assistant Division Chief for Census Programs. Branch Chiefs 

and Special Assistants: Bashiruddin Ahmed, Joshua Comenetz, Frank B. Hobbs, Nicholas Jones, 

Marie Pees, Marc Perry, Roberto R. Ramirez, David W. Sheppard, Amy Symens Smith, Janice A. 

Valdisera. Other Contributors: Nora Albert, Maryam Asi, Daniel Beaulieu, Angela Brittingham 

Buchanan, Kristin D. Burnett, Paul R. Campbell, Linda Chase, Darryl Cohen, Craig S. Cruse, 

Warren F. Davis, Sharon Ennis, Denise Flanagan-Doyle, Thomas Fischetti, John T. Fitzwater, 

Delma T. Frankel, Justyna Goworowska, Geoffrey W. Hatchard, Brad Hepler, Lindsay Hixson, 

Elizabeth Hoeffel, Charles Holmberg, Lindsay Howden, Colleen T. Hughes, Jonathan Jackson, 

Marcella Jones-Puthoff, Kay T. Jung, Susan M. Keehan, Myoung Ouk Kim, Brian Kincel, Ashley T. 

Landreth, Robert M. Leddy Jr., Paul J. Mackun, Rachel Marks, Leanna Mellott, Julie Meyer, Tina 

Norris, Sonya Rastogi, Merarys Rios, Hasan Shahid, Linda M. Showalter, Rita Stephan, Julie A. 

VanEerden, Paula Vines, Carrie Werner, Steven G. Wilson, Janet L. Wysocki.

The Social, Economic, and Housing Statistics Division, David S. Johnson, Division Chief; Arthur R. 

Cresce Jr., Assistant Division Chief for Housing Characteristics; Robert A. Kominski, Assistant Division 

Chief for Social Characteristics; Branch Chiefs: Rose Kreider, Martin O’Connell, Jeanne Woodward. 

Other Contributors: William S. Chapin, Reita Glenn Hackett, Kristy Krivickas, Daphne A. Lofquist, 

Terry Lugaila, Christopher R. Mazur, Mary Schwartz, Ellen Wilson.