TIGER/Line(TM) Files, 1992

                         Chapter 3:

      Geographic Objects in the TIGER/Line(TM) File
Line Features

Feature Identifiers

Identification

The "feature identification" fields contain either a 
general type label or a specific proper name assigned to a 
complete chain that identifies the feature.  Each complete 
chain that comprises a named feature, such as US Highway 1, 
has the same feature identifier.  The TIGER/Line(TM) files 
do not support a data level above the complete chain that 
allows the construction of higher level objects (features).  
Note that complete chains with the same name may represent 
separate features; for example, a county may contain 
several Main Streets located in different geographic 
entities (e.g., towns or cities) scattered throughout the 
county.

The ability to group chains together to include the entire 
length of a street feature, such as US Route 66, depends on 
the uniqueness of the identifiers and the consistency of 
the feature identifiers along the length of the feature.  
The Census Bureau makes no guarantee that the complete 
chains have uniform names or contain all of the known 
feature identifiers.

Also note that the Census Feature Class Codes (CFCC's) may 
vary for chains with the same feature identifier.  For 
example, the most frequent CFCC for a state highway is A21, 
but the complete chains marking the location of State 
Highway 32 may have a CFCC of A01, A40, or A21 (see the 
section on Census Feature Class Codes, Chapter 3).

The TIGER/Line(TM) files use several related data fields to 
provide a structured description of the feature identifier:

  *  Feature Direction Prefix (e.g., N. Adams Ave.)

  *  Feature Name (e.g., US Highway 1, Jefferson St.)

  *  Feature Type (Roosevelt Blvd., Mangosteen River)

  *  Feature Direction Suffix (e.g.,  Providence St. N.E.)

Most named street/highway features have a feature type.  
Numerous exceptions exist; for example, "Broadway" consists 
of a feature name with no type specified.  Do not confuse 
feature types that form proper names with the CFCC 
classification scheme.

The feature identifiers may include either a direction 
prefix or suffix.  Some may have both a direction prefix and 
suffix.

The feature name fields may contain both a name and a 
feature type.  For all hydrography and for all non-road 
features, the feature type normally will follow the feature 
name in the feature name field.  In some instances, the 
type is commonly considered part of the name and is 
combined with the feature name in TIGER/Line(TM) files to 
avoid confusion; for example, US Hwy 1.  The TIGER System 
identifies "US Hwy" as a feature type used as a prefix to 
the name and "1" as the feature name.  Note that the 
feature types such as US Highway, State Highway, and 
Interstate, normally precede the name, appear in the name 
field, and are excluded from the Standard Feature Types 
list below.

Generic feature identifiers have a name listed in the names 
field, but do not have a feature type or direction.  Some 
examples of generic names include:

  *  Ramp
  *  Power line
  *  Reservoir

Generic feature identifiers were selectively added to 
features that do not have proper names.  In most cases, 
complete chains without proper names will have no feature 
identifier.

The TIGER/Line(TM) file structure allows up to 4,996 
feature identifiers for a complete chain.  The primary 
feature identifier appears in Record Type 1.  For street 
features, the primary feature identifier is usually the 
name most commonly associated with the address range.  Up 
to five alternate feature identifiers are cross-referenced 
in each Record Type 4 record, and a single complete chain 
can have up to 999 Record Type 4 records.  Alternate 
feature identifiers include highway designation numbers for 
named streets, former names, and alternate spellings where 
source material provided conflicting data.

Where the complete chain represents a limited access 
highway, the highway type and route designator, such as 
I-95, should ideally become the primary name, and the local 
designation, such as Cross County Expressway or Capital 
Beltway, should become the alternate name.  However, this 
is not always true in the TIGER/Line(TM) files.

The primary and alternate feature identifiers can be 
independent of each other.  There is no assurance that the 
same combination of primary and alternate feature 
identifiers will appear together on sequence of complete 
chains.  There also is no assurance that a feature 
identifier will consistently appear as the primary 
identifier; it might be recorded as an alternate feature 
identifier for some complete chains and a primary feature 
identifier for others.

Record Type 5 contains a record for each feature identifier 
used as either a primary or an alternate name.  The 
TIGER/Line(TM) files link the alternate names in Record 
Type 5 to Record Type 1 through the use of the alternate 
feature identification code index that forms Record Type 4.  
See the section on Feature Name Record Linkage in Chapter 
3.

Record Locations:  Feature Identifiers

   RT     Field Name        Description

    1       FEDIRP          Directional (prefix type)
    1       FENAME          Primary feature name 
    1       FETYPE          Feature type
    1       FEDIRS          Directional (suffix type)
    5       FEDIRP          Directional (prefix type)
    5       FENAME          Alternate and primary feature
                            name 
    5       FETYPE          Feature type
    5       FEDIRS          Directional (suffix type)

Codes:  Feature Identifier

Directionals (Prefix and Suffix)

Directionals consist of a 2-character abbreviation.

   Abbreviation  Explanation

   (Blank)       No Direction
   N             North, Norte
   S             South, Sur
   E             East, Este
   W             West, Oeste
   NE            Northeast, Norte Este, Nordeste
   NW            Northwest, Norte Oeste, Noroeste
   SE            Southeast, Sur Este, Sudeste
   SW            Southwest, Sur Oeste, Sudoeste
   EX            Extended, Extension

Feature Names

Feature names consist of a 30-character text string with 
words separated by blanks.  Feature names contain upper- 
and lower-case characters.  The feature name is 
truncated if it is over 30 characters long.

For Puerto Rico, the TIGER/Line(TM) file contains the 
following codes to represent diacritical marks:

   ]  Preceding character has acute accent ()
   [  Preceding character has dieresis ()
   #  Preceding character has tilde (~)

The names field may contain abbreviations to represent 
some feature types.  See Appendix D - Standard 
Abbreviations and the list of Standard Feature Types 
below.

Feature Types 

The feature type field consist of a 4-character text 
string.  For all hydrography and for all non-road 
features, the feature type normally will follow the 
feature name in the feature name field.  The following 
abbreviations may appear in the feature type field or 
the feature name field.  If the feature type is not one 
of the types that appears in the following list, the 
feature type will appear in the feature name field.

   Standard Feature Types

   Abbr.       Name                    Abbr.       Name

   Al          Alley                   Park        Park
   Arc         Arcade                  Pkwy        Parkway
   Ave         Avenue, Avenida         Pass        Pass
   Blvd        Boulevard               Path        Path
   Br          Branch                  Pike        Pike
   Brdg        Bridge                  Pl          Place
   Byp         Bypass                  Plz         Plaza
   C           Calle                   Pt          Point
   Cswy        Causeway                Ramp        Ramp
   Ctr         Center                  Road        Road
   Cir         Circle                  Row         Row
   Ct          Court                   Rue         Rue
   Cove        Cove                    Skwy        Skyway
   Cres        Crescent                Sq          Square
   Crsg        Crossing                St          Street
   Dr          Drive                   Ter         Terrace
   Exwy        Expressway              Thwy        Throughway
   Frwy        Freeway                 Tfwy        Trafficway
   Hwy         Highway                 Trl         Trail
   Loop        Loop                    Tpke        Turnpike
   Mall        Mall                    Unp         Underpass
   Mtwy        Motorway                Wall        Wall
   Oval        Oval                    Walk        Walk
   Ovps        Overpass                Way         Way
   Pkwy        Parkway


Data Limitations and Notes

In the GBF/DIME-File coverage areas, users may not find 
many roads with alternate names; if an alternate name is 
provided, it usually represents another local name and not 
a route number.

Corporate Corridors and Corporate Offset Boundaries

A corporate corridor is a narrow, linear part of an 
incorporated place.  The corporate corridor includes the 
street and/or right-of-way or a portion of the street 
and/or right-of-way within the incorporated place.  It 
excludes from the incorporated place those structures, such 
as houses, apartments, or businesses, that front along the 
street or road.

A corporate limit offset boundary exists where the 
incorporated place lies on one side of the street and 
includes all or part of the street and/or right-of-way, but 
excludes from the incorporated place the structures located 
along that side of the street.  See the section on Places, 
Chapter 4.

To facilitate address coding, the Census TIGER data base 
contains duplicate street name and address ranges on 
complete chains with a CFCC of F11, (nonvisible offset 
boundary) or F12 (nonvisible corporate corridor).  The 
duplicate street names for the F11 and F12 features are on 
Record Type 5.  Record Type 1 will not contain feature 
identifiers for complete chains with CFCC's of F11 or F12.

Feature Identifier Record Linkage 

Concepts

Record Type 4 provides the link required to find any 
alternate feature identifiers belonging to a complete 
chain.  Record Type 4 cross references each TLID with an 
Alternate Feature ID code (FEAT) assigned to each record 
in Record Type 5.  Record Type 5 contains all feature 
identifiers including those that are used only as 
primary identifiers.  However, only the FEAT's for 
complete chains that have alternate feature identifiers 
appear in Record Type 4.  Complete chains that have no 
alternate feature identifier will have no Record Type 4 
record.

To find the alternate feature identifiers for a complete 
chain, begin by determining the TLID for the complete 
chain.  Then search for this TLID in Record Type 4.  If 
the complete chain has any alternate feature identifiers, 
Record Type 4 should provide at least one record.

Once found, the Record Type 4 entries will each contain 
from one to five FEAT numbers.  The feat fields are 
blank when no further alternative identifiers exist.  
The first FEAT field (FEAT1) should always have a valid 
FEAT number.  Finally find the records in Record Type 5 
file that match the FEAT codes from Record Type 4.  The 
TIGER/Line(TM) file provides a record sequence number to 
identify multiple Record Type 4 records that might exist 
for one TLID.

Even though Record Type 5 contains all feature 
identifiers, Record Type 4 contains only references for 
alternate feature identifiers.  Data users cannot link 
all of the names in Record Type 5 to all of the 
associated complete chains in Record Type 1 by using 
Record Type 4.

Record Locations:  Feature Identification Numbers

   RT     Field Name        Description

    1       TLID            Permanent record number
    4       TLID            Permanent record number
    4       RTSQ            Record Type 4, record sequence 
                            number 
    4       FEAT1           Alternative feature
                            identification code #1
    4       FEAT2           Alternative feature
                            identification code #2
    4       FEAT3           Alternative feature
                            identification code #3
    4       FEAT4           Alternative feature
                            identification code #4
    4       FEAT5           Alternative feature
                            identification code #5
    5       FEAT            Alternate and primary feature
                            identification codes

Codes:  Feature Identification Numbers

The FEAT data field contains an 8-digit integer number 
(without leading zeros).  The TIGER/Line(TM) files 
assigns a FEAT to each feature identifier in Record Type 
5 sequentially beginning with 1 in each TIGER/Line(TM) 
file.  The FEAT is not a permanent identification 
number.

TLID is the record identifier for the complete chain.  
See Chapter 2 for a full discussion of TLID's.

RTSQ is a 3-digit integer number that uniquely 
identifies multiple Record Type 4 records with the same 
TLID.  RTSQ equals 1 for the first occurrence of a TLID 
in Record Type 4 and can reach a maximum of 999 for 
subsequent occurrences.

Address Ranges and ZIP Codes(R)

Identification

The TIGER/Line(TM) files contain address ranges rather than 
individual addresses.  The term "address range" refers to 
the first possible structure number and the last possible 
structure number along a complete chain side relative to 
the direction in which the complete   chain is coded.  The 
address ranges in the TIGER/Line(TM) files are 
predominantly potential ranges that include the full range 
of possible structure numbers even though the actual 
structures might not exist.

The address numbers used to create the address ranges are 
commonly known as city-style addresses.  A city-style 
address consists of a structure number, street name, and a 
ZIP Code(R), for example; 213 Main St. 90210.  In the 
TIGER/Line(TM) files, the ZIP Codes(R) appear only on those 
complete chains that have address ranges identified.

Address Ranges -- Complete chains in the TIGER/Line(TM) 
files have one end point labeled as the "start" node and 
the other end point labeled as the "end" node.  The "start" 
and "end" nodes also are referred to as "from and "to."  
The "start" node always corresponds to the beginning of the 
complete chain identified by the "start" node coordinates 
FRLAT and FRLONG.  The order of the addresses follows the 
sequence of the nodes on the complete chain and is not 
related to the low to high orientation of the address 
range.  The "start" address may be higher or lower than the 
"end" address for a complete chain.  Structure numbers 
usually, but not always, systematically increase or 
decrease while moving down a street in a set direction from 
one complete chain to the next.

Record Type 1 contains the initial address ranges for the 
left and right sides of a complete chain.  A complete chain 
side may have multiple address ranges.  The TIGER/Line(TM) 
files use record type 6 to store any additional ranges as 
required.  The Record Type 1 record will hold the ranges 
with the largest sequence of numbers.  However, Record Type 
6 may hold a significant number of additional ranges.  Data 
users must use Record Type 6 to obtain the complete picture 
of the possible address ranges along a complete chain.

In Record Types 1 and 6, the left- and right-side address 
ranges each have a "start" and an "end" address range field 
that can contain a maximum of 11-alphanumeric characters.  
The address range fields are right-justified.

Each address range in the TIGER/Line(TM) files has only one 
parity.  Only odd-numbered addresses are contained within 
an address range with odd "start" and odd "end" structure 
numbers.  Likewise, only even-numbered addresses belong to 
an address range with even "start" and "end" structure 
numbers.  Generally, the left and right sides of a complete 
chain will have opposite parities.  If both odd and even 
addresses exist on the same side of a complete chain, the 
TIGER/Line(TM) will provide both an even and a separate odd 
parity range for that side of the complete chain.  One of 
the ranges may appear in Record Type 1, or Record Type 6 if 
other ranges exist for the file, while the other will 
appear separately in Record Type 6.

Some address ranges may include single value ranges, such 
as 16-16, referred to as an "include" address.  These 
"include" addresses are anomalies; they may have a parity 
opposite to the prevailing address range on the complete 
chain side, or appear as an outlier from an adjoining range 
that does not fit within the range belonging to the 
complete chain where it is located.  For example, the 
location of 16 Osage St. falls on the odd-numbered side of 
the street with address range 1-99.  The range 16-16 will 
appear as an additional "include" range on the left side of 
the street.  The even address range 2-98 on the right side 
of the street must exclude the number 16 structure number; 
the right address range becomes two ranges:  2-14 and 18-
98.  Outliers follow the same pattern.  For example, 10 
Persimmon St. may appear on the side of the complete chain 
with the range 100-198 and not on the complete chain with 
the range 2-98.  As before, 10-10 would become an 
additional range added to the complete chain with the range 
100-198, and the address range 2-98 will become two ranges:  
2-8 and 12-98.  Because "include" address ranges require 
complex edits that would possibly involve several complete 
chains, the Census Bureau cannot guarantee that all 
duplications of addresses were identified and eliminated.

Some basic characteristics of address ranges are as follows:

  *  The TIGER/Line(TM) file contains only those city-style 
     address ranges used for mail delivery.  It does not show 
     rural route and post office box addresses, or structure 
     numbers assigned in select areas for emergency use only.

  *  Gaps may exist between multiple ranges for a single 
     complete chain.  A gap may be significant, since any 
     numbers missing from one complete chain may actually 
     appear on another complete chain, in the case of an 
     address anomaly such as out of parity or out of sequence 
     addresses.

  *  Address ranges (consisting of a unique combination of 
     structure number, ZIP Code(R), feature name, feature 
     type, and directional) should not overlap; addresses 
     should belong only to one range.  The Census Bureau 
     edits the address ranges to locate possible overlaps, 
     but cannot guarantee that all possible overlap 
     situations have been identified.

  *  Address ranges exist only for street features and in 
     some cases corporate corridor and corporate offset 
     boundary features.

  *  Address ranges in the TIGER/Line(TM) files are 
     associated with both the primary and alternate feature 
     identifiers.

  *  In a few rare cases, address ranges can include 
     numbers with alphabetic characters.  These characters 
     help uniquely identify the address within the county.  
     For instance, certain unincorporated areas of Genesee 
     County, Michigan prefix the address number with the 
     letter "G."  The characters are consistently placed 
     within the address range field; for example, the letter 
     G maintains a consistent column placement in the range 
     "G 1" to "G99".

Some address systems use the "-" character to separate 
avenue numbers, private road designators, and grid cell 
numbers from the structure numbers; for example, 10-01 
Reynolds St. uses a hyphen to separate the avenue number 
from the structure number.

See Figures 3-1 through 3-3 for examples of the different 
address range situations and how they are coded in the 
TIGER/Line(TM) files.

Imputed Address Ranges -- Imputed address ranges occur 
during the process of updating the Census TIGER data base, 
when a new complete chain intersects an existing complete 
chain with address ranges.  The intersection splits the 
existing complete chain and produces two new complete 
chains connected by a new node located at the intersection 
point.  The update program divides the old address ranges 
among the two new complete chains and "imputes" the address 
range ends at the new node.  The impute process allocates 
parts of each original address range to each of the 
complete chains in proportion to their lengths.  Where a 
complete chain has multiple address ranges, the update 
program imputes address range breaks for each original 
address range independent of the other address ranges and 
without regard to the actual location of the addressed 
structures along the street.  See Figure 3-4 for an example 
of an imputed address range.

Census Bureau staff also identified some ranges as imputed 
during an address range coding and correction operation 
prior to the 1990 census.  These imputed address ranges 
appear in situations where the address reference sources 
showed a single range covering several complete chains that 
form the same block side in the Census TIGER data base.    
A typical example occurs with "T" intersections; the 
reference source might provide one range that would span 
the top of the "T" where the Census TIGER data base shows 
two complete chains.  The use of impute flags indicates 
that the assignment of the reference source range to one or 
more of the complete chains was arbitrary.

The impute/source flags identify address ranges that have 
been through the impute process.  Each record in the 
TIGER/Line(TM) files contain four separate 1-character 
impute/source flag fields, one for each address range end.  
For the 1992 TIGER/Line files, the possible flag values are 
extended to identify the address range source as well as 
imputed address values.  The flags distinguish between 
those ranges created from information contained in the 1990 
census ACF from those that were already present in the 
Census TIGER data base before that operation (see the 
Address Information Methodology subsection for more details 
on ACF address ranges).

ZIP Codes(R)-- The ZIP Code(R) is a complete chain attribute 
that only exists for complete chains that have address 
ranges.  The TIGER/Line(TM) files have a 5-character ZIP 
Code(R) field containing a numeric code with leading zeros.  
Each address range belonging to a complete chain can have a 
different ZIP Code(R).  Since the ZIP Codes(R) in the 
TIGER/Line(TM) file relate to mail delivery along addressed 
streets, they are not true area features.  It is possible 
that a polygon may contain addresses associated with more 
than one delivery ZIP Code(R).

NOTE:  Where streets form ZIP Code(R) boundaries, the 
complete chain has different left and right side ZIP 
Codes(R).  The Census TIGER data base contains only one ZIP 
Code(R) for each address range record.  Address ranges with 
different ZIP Codes(R) must therefore appear in separate 
records.  The address range(s) with one ZIP Code(R) will 
appear in Record Type 1, and the other address range(s) 
with the other   ZIP Code(R)(s) will appear in Record Type 
6.  For example, one complete chain making up Duke Street 
is a ZIP Code(R) boundary; the left side range 1-99 has ZIP 
Code(R) 12345, and the right side range 2-98 has   ZIP 
Code(R) 54321.  The range 1-99 with ZIP Code(R) 12345 will 
appear in Record Type 1; note that the right-side range 
fields will be blank.  The range 2-98 with ZIP Code(R) 
54321 will appear in Record Type 6; note this time that the 
left-side range fields will be blank.  If the complete 
chain held additional address ranges with either ZIP 
Code(R) 12345 or 54321, they would appear with the existing 
range or as an additional Record Type 6 record.  For 
example, a right-side range of 150-198 with   ZIP Code(R) 
12345 could appear on the Record Type 1 record with the 
range 1-99.  However, a right-side range of 150-198 with 
ZIP Code(R) 54321 could not appear on the Record Type 6 
record with the range 2-98.  Instead, the range must appear 
in a second Record Type 6 record.

Address Information Methodology

Pre-1990 Census Address Ranges -- Before the 1990 census, 
the Census TIGER data base contained address range coverage 
only for the area covered by GBF/DIME-Files and a few file 
extension area.  The Census Bureau obtained the address 
ranges from reference sources and the GBF/DIME-File before 
the 1990 canvassing operations.  These ranges were used to 
geocode a list of addresses to geographic areas for use in 
questionnaire mail-out.

The Census Bureau purchased the list of addresses from 
commercial vendors for the geographic areas where the 
Census TIGER data base included address ranges.  To verify 
the accuracy of the addresses, the Census Bureau began with 
an initial assignment of residential addresses to the 1990 
census tracts and blocks.  Clerical review of the results 
of the assignment process resulted in additional address 
range updates.  All of the address ranges in the Census 
TIGER data base coming from the GBF/DIME-Files, the file 
extension areas, and the clerical review process are 
identified in the TIGER/Line(TM) file by impute/source flag 
values of 0 or 1.

Although an address range in the TIGER/Line(TM) file may be 
incorrect, the Census Bureau implemented procedures to 
ensure that the error did not adversely affect the accuracy 
or the quality of the 1990 census.  In later field 
operations, enumerators verified, corrected, and updated 
the list of addresses assigned to each block by walking the 
perimeter and all interior streets of each block and 
checking the list against their observations.

Expanded Addresses -- The Census Bureau has expanded the 
address range coverage for the entire United States by 
creating new ranges based on the ACF used in the 1990 
decennial census.  The ACF is a master list of addresses 
geocoded to the census block level.  For each block, the 
individual structure addresses were grouped by feature 
identifier and sorted into numerical order to extract an 
actual range.  The order of the addresses relative to the 
start and end nodes comes from the order of addresses for 
the street feature as a whole (i.e., the collection of 
linked complete chains with the same feature identifier).  
Likewise, the overall parity of the street feature sets the 
standard for identifying and editing anomalies along the 
complete chains.

To maintain confidentiality of individual addresses, the 
Census Bureau converted the actual range to a potential 
range by expanding the range to complete a hundred range, 
split the difference between coverage gaps, and in some 
cases disguised the range by the random addition or 
subtraction of addresses.

The Relationship Between Pre-existing and ACF Address 
Ranges -- Where a complete chain contains both an ACF and a 
pre-existing address range in the Census TIGER data base, 
the pre-existing address range appears in the 1992 
TIGER/Line files.  A complete chain that contains a mixture 
of ACF and non-ACF ranges will show entire ACF based 
address range on a complete chain side with only an ACF 
based address range.  For example, a complete chain has the 
following addresses in the Census TIGER data base:  a non-
ACF range of 1-99 on the left side, and the ACF ranges 1-
107 on the left side, and 50-108 on right side.  In the 
1992 TIGER/Line files, the non-ACF range will appear on the 
left side, but the ACF based range 50-108 will appear on 
the right side.  No attempt has been made to resolve 
differences between the two sources.  The ACF range may 
create overlaps with non-ACF ranges on the adjoining 
complete chains.


Record Locations:  Address Ranges

   RT     Field Name        Description

    1       FRADDL          "Start" address (left side of 
                            complete chain)
    1       TOADDL          "End" address (left side of
                            complete chain)
    1       FRADDR          "Start" address (right side of
                            complete chain)
    1       TOADDR          "End" address (right side of 
                            complete chain)
    6       FRADDL          Additional "start" address (left
                            side of complete chain)
    6       TOADDL          Additional "end" address (left
                            side of complete chain)
    6       FRADDR          Additional "start" address (right
                            side of complete chain)
    6       TOADDR          Additional "end" address (right
                            side of complete chain)

Record Locations:  Impute Flags

   RT     Field Name        Description

    1       FRADDL          "Start" address flag (left side 
                            of complete chain)
    1       TOIADDL         "End" address flag (left side of
                            complete chain)
    1       FRIADDR         "Start" address flag (right side
                            of complete chain)
    1       TOIADDR         "End" address flag (right side of
                            complete chain)
    6       FRIADDL         "Start" address flag for
                            additional range (left side of 
                            complete chain)
    6       TOIADDL         "End" address flag for additional
                            range (left side of complete
                            chain)
    6       FRIADDR         "Start" address flag for 
                            additional range (right 
                            side of complete chain)
    6       TOIADDR         "End" address flag for additional
                            range (right side of complete 
                            chain)

Record Locations:  ZIP Codes(R)

   RT     Field Name        Description

    1        ZIPL           5-digit ZIP Code(R) (left side of
                            complete chain)
    1        ZIPR           5-digit ZIP Code(R) (right side
                            of complete chain)
    6        ZIPL           5-digit ZIP Code(R) for
                            additional range (left side of
                            complete chain)
    6        ZIPR           5-digit ZIP Code(R) for 
                            additional range (right side of 
                            complete chain)

Codes:  Address Ranges and Impute Flags

Address Ranges

  *  Numeric characters or a mixture of numeric and 
     alphabetic characters (maximum of 11 characters)

  *  Ranges beginning or ending with zero (0) are not 
     valid 

  *  Address range fields are blank when no address 
     range is available.  Both the "start" and "end" 
     address range fields are blank or have non-zero 
     values.  One field is not blank while the other 
     contains a valid address.

Impute Flags/Source Flags (1-character numeric code)

  *  No address range available                           " "

  *  Not imputed, address range derived from 
     reference sources                                    "0"

  *  Imputed, address range derived from reference 
     sources                                              "1"

  *  Not imputed, address range derived from the 1990 
     census ACF                                           "2"
  *  Imputed addresses, derived from 1990 census ACF      "3"

ZIP Codes(R)

See U. S. Postal Service (USPS) Publication 65, National 
Five-Digit   ZIP Code and Post Office Directory for a list 
of valid 5-digit ZIP Codes(R).  The 1992 TIGER/Line files 
will not contain delivery ZIP Codes(R) established since 
the 1990 census operations or non-delivery ZIP Codes(R).  The 
distribution of ZIP Codes(R) in the TIGER/Line(TM) files   
may not reflect the exact USPS ZIP Code(R) service area.

Limitations

Users of the TIGER/Line(TM) file's address ranges should 
check for address range overlaps, gaps, odd/even reversals, 
and other situations that may be incorrect.

Corporate Corridors and Corporate Limit Offset Boundaries

A corporate corridor is a narrow, linear part of an 
incorporated place.  The corporate corridor includes the 
street and/or right-of-way or a portion of the street 
and/or right-of-way within the incorporated place.  It 
excludes from the incorporated place those structures, such 
as houses, apartments, or businesses, that front along the 
street or road.

A corporate limit offset boundary exists where the 
incorporated place lies on one side of the street and 
includes all or part of the street and/or right-of-way, but 
not the structures located on that side of the street.  See 
the section on Places, Chapter 4.

To facilitate the coding of address to the correct 
geographic entity, the Census TIGER data base contains 
duplicate street name and address ranges on complete chains 
with a CFCC of F11 (nonvisible offset boundary) or F12 
(nonvisible corporate corridor).  The duplicate street 
names for the F11 and F12 features are on Record Type 5, 
and the duplicate address ranges are on Record Type 6.  
Complete chains with CFCC's of F11 or F12 will not contain 
the duplicated names or address ranges in Record Type 1.  
Record Type 1 does not indicate that the street or right-
of-way lies within a corporate corridor or offset boundary 
and that the address ranges lie outside the corporate 
corridor or offset boundary and are encoded on either side 
of these lines.  Data users planning to geocode addresses 
in areas with these boundary types must identify the 
duplicated feature identifiers and ranges from Record Type 
5 and 6 (the names and address ranges for CFCC F11 and F12 
features), locate the street feature with that range, and 
remove the street feature's address ranges and geographic 
codes from the geocoding process.

Record Linkages

The TIGER/Line(TM) files store address range information in 
two record types.  Record Type 1 contains the basic complete 
chain attributes, including one basic address range.  Record 
Type 6 stores the additional ranges when the complete chain 
has more that one range on one or both sides.

The TLID field links Record Types 1 and 6.  Since a complete 
chain can have more than one set of ranges, multiple Record 
Type 6 records can exist with the same TLID.  The 
TIGER/Line(TM) files distinguish these records with a record 
sequence number (RTSQ).  All Record Type 6 records that have 
the same TLID appear sequentially in the file even though the 
records are not sorted by TLID.  The TIGER/Line(TM) files do 
not contain a field indicating whether a Record Type 6 record 
exists for a specific TLID; the user must scan any existing 
records in Record Type 6 for a TLID match.

Boundaries of Geographic Entities

Identification

The TIGER/Line(TM) files store geographic codes as either a 
polygon or complete chain attribute.  In the case of State 
and county level geography, the codes appear in both 
complete chain and polygon record types.  To learn more 
about the available complete chain attribute codes, refer 
to the description of Record Types 1 and 3 in Chapter 6; or 
see the description of Record Types A, F, and G also in 
Chapter 6 for a list of polygon attribute codes.  To find 
out what codes are available for a specific level of 
geography, see Chapter 4.

Record Linkages and Boundary Extraction

The codes assigned to the complete chain belong to the 
areas referenced by the left and right sides of a complete 
chain.  Only those features that have different geographic 
codes on the left and right sides of a line become boundary 
features.  Some geographic entities require information 
from multiple TIGER/Line(TM) data fields in order to 
uniquely identify that entity's boundary.  For instance, 
both the census block and census tract/BNA codes are 
required to identify a block boundary.  For instance, block 
101 in census tract 2101 could neighbor block 101 in census 
tract 2998.  Be sure to use both the basic number and 
suffix when extracting either census tract or block 
boundaries.  Data users who have combined TIGER/Line(TM) 
files should include the county/county equivalent code to 
extract census tract/BNA boundaries.

The extraction of boundary features from polygon attribute 
codes requires making a link between the polygon and the 
complete chain data records, and then identifying the 
features with different left- and right-side geographic 
codes.  For a description of the record linkage process, 
see the section on Record Linkages to Polygons and Chains, 
in Chapter 3.

Boundary rings consist of multiple complete chains that are 
sequentially linked together and connect to form a closed 
ring.  The process of linking all of the boundary complete 
chains that outline the same geographic entity requires the 
extraction of all complete chains that have that entity's 
code on either the left or right side (but not both).  
Linking the chains together will form a polygon; each 
polygon may represent one of the GT-polygons described in 
Record Types A and P, or a collection of those GT-polygons.  
Record Types A and P describe only the most elementary 
polygons.

Caution:  Some types of geographic areas must end at a 
county/file boundary while others can continue into 
adjoining counties/files.  For example, MCD's stop at a 
county boundary, whereas incorporated places can exist in 
several counties (See the section on Record Linkages/ 
Feature Chaining).

Single-Side Flags and County Boundaries

The TIGER/Line(TM) files use the 1990 counties/county 
equivalents as   the basis for the file coverage area.  The 
boundaries do not reflect post-1990 census corrections or 
changes.  Each county file contains all of the codes relevant 
to that county.

County boundary features are duplicated between adjoining 
pairs of counties so that each file is complete.  However, 
the complete chains that constitute the boundary features 
contain only the geographic entity codes and address ranges 
relevant to each county based TIGER/Line(TM) file.  The 
geographic entity codes are blanked out on the outside edge 
of the county, even though some of these fields must normally 
have a non-blank code.  The TIGER/Line(TM) file identifies 
these complete chains with a 1-character, "single side 
segment flag."

When combining several TIGER/Line(TM) files to form a State 
or regional data set, the data user will need to eliminate 
duplicate boundary lines.  Because each one of the duplicate 
boundary complete chains has either the left- or right-side 
geographic entity codes and address ranges, the elimination 
process will need to combine the codes and address ranges 
from both lines.

The same situation applies to the polygon identification 
codes.  Record Type I contains CENID's and POLYID's for GT-
polygons within the county.  If the GT-polygon is in the 
adjacent county, the CENID and POLYID fields are blank.
Record Locations:  Single-Side Flag

   RT     Field Name        Description

    1       1SIDE           flag 

Codes:  Single-Side Flag

  The complete chain is a county boundary                 "1"
  The complete chain is not a county boundary             " "

CFCC's

Identification

The CFCC is a 3-character classification code that provides a 
basic feature description.  All complete chains and landmarks 
have a CFCC.  GT-polygons do not have a CFCC unless they are 
associated with an area landmark.

In the portion of the TIGER/Line(TM) file prepared from the 
GBF/DIME-Files, the roads are classified as Class 4 roads 
with a few exceptions.  The interstate highways that were 
identified by name in the GBF/DIME-File are classified as 
Class 1 roads.

Record Locations:  CFCC

   RT     Field Name        Description

    1       CFCC            Code assigned to the complete
                            chain

Codes:  CFCC's

Appendix E lists the potentially available CFCC's.  The 
list of CFCC's provides for the possible inclusion of these 
types of features.  For example, a property line (F40) will 
appear in the file only when a statistical or political 
boundary is known to follow that property line.  Note that 
most CFCC's refer only to complete chains while others may 
describe only entity points (point landmarks) or area 
landmarks.   In a few cases, the same CFCC can apply to 
entity points, complete chains, and area landmarks.
CFCC's Used for Both Complete Chains and Landmarks

  CFCC  Description

  D00  Landmark feature, classification unknown, or not  
       elsewhere classified

  D50  Transportation terminal
  D51  Airport or airfield

  H10  Stream
  H11  Perennial stream
  H12  Intermittent stream or wash
  H13  Braided stream 

  H20  Canal, ditch, or aqueduct
  H21  Perennial canal, ditch, or aqueduct
  H22  Intermittent canal, ditch, or aqueduct

Points Describing the Complete Chain

Identification

The TIGER/Line(TM) files describe the spatial/geometric 
position and shape of a complete chain using shape points 
and nodes; see the discussion on TIGER topology in Chapter 
1.  Latitude and longitude coordinate fields identify the 
shape points and nodes.  The Census TIGER data base does 
not support node identification numbers.

Nodes -- Nodes are topological objects that mark the end 
location of each complete chain.  Every chain has two 
nodes, a "start" node and an "end" node (using the SDTS 
terminology).  Earlier releases of the TIGER/Line(TM) files 
refer to theses nodes as the "from" node and the "to" node.  
The order of the nodes establishes left and right sides of 
the line and sets the sequencing order for the shape points.  
The node coordinates are stored in Record Type 1.

Shape Points -- The Census Bureau uses the term "shape 
points" to describe the non-topological points that 
describe the position and shape of a chain.  Shape points 
exist only where required; straight line complete chains 
require no shape points.  Shape points are associated only 
with one complete chain and are listed in order from 
"start" node to  "end" node.  The TIGER/Line(TM) files 
store shape points in Record Type 2 and links them to the 
nodes in Record Type 1 using the TLID.  The shape points 
for a chain can fill several Record Type 2 records.


Coordinates for Nodes and Shape Points

Coordinates are expressed in standard FIPS notation, where 
a positive latitude represents the Northern Hemisphere and 
a negative longitude represents the Western Hemisphere.  
All coordinates are expressed as   a signed integer with 
six decimal places of precision implied.

  Actual                          TIGER/Line(TM) File

  Latitude 15 Deg. S to 72 Deg.   N -15000000 to +72000000
  Longitude 64 Deg. W to 131 Deg. E -64000000 to -180000000
                                   +131000000 to +179999999

The TIGER/Line(TM) files use coordinates based on the North 
American Datum of 1927 (NAD27) (see reference McKenzie and 
LaMacchia, 1987).

Beginning with the 1990 Census TIGER/Line files, the + and - 
signs appear to the left of the left-most digit with the 
preceding character blank-filled if it is not in use in the 
field.  The representation is now "standard" FORTRAN where 
the sign "floats" in front of the number.

Please note that the Census Bureau changed the way the + and 
- signs appear in the coordinate fields beginning with the 
1990 Census TIGER/Line files.  In the TIGER/Line(TM) Files 
Initial Voting District Codes, 1990 the + and - signs were 
fixed in the left-most character position of the field.

  Example:  " +98123456"     1990 Census TIGER/Line file 
                             and later versions

            "+ 98123456"     TIGER/Line(TM) File Initial 
                             Voting District Codes, 1990

Record Locations:  Coordinates for Nodes and Shape Points

   RT     Field Name        Description

    1      FRLONG           Start node (or "from" node)
                            longitude
    1      FRLAT            Start node (or "from" node)
                            latitude
    1      TOLONG           End node (or "to" node) longitude 
    1      TOLAT            End node (or "to" node) latitude
    2      LONG1            1st shape point longitude
    2      LAT1             1st shape point latitude
    2      LONG2            2nd shape point longitude
    2      LAT2             2nd shape point latitude
    2      LONG3            3rd shape point longitude
    2      LAT3             3rd shape point latitude
    .        .              .
    .        .              .
    .        .              .
    2      LONG10           10th shape point longitude
    2      LAT10            10th shape point latitude

Values:  Coordinates

All nodes have non-zero coordinates within the range 
specified above.  Shape point coordinates are expressed in 
the same manner.  However, unused Record Type 2 fields are 
zero filled with a "+" sign.

Record Linkages/Feature Chaining

The plotting of a complete chain requires using the nodes 
from Record Type 1 and all of the shape point records in 
Record Type 2 with the same  TLID if any.  Plot start node 
first.  Search Record Type 2 for any matching records.  If 
there is a match, the record will contain from 1 to 10 shape 
points.  If all 10 point fields are filled with non-zero 
values, then there may be an additional matching Record Type 
2 record.  Record Type 2 records are not sorted by TLID, but 
all records with the same TLID should appear together in 
sequence by the record sequence number (RTSQ).  Plot the 
shape points from all Record Type 2 records and end the 
complete chain by plotting the end node.

Street features may consist of multiple complete chains that 
are sequentially linked together.  Linking all of the 
features with the same name requires the extraction of all 
Record Types 1 and 2 records with the same feature 
identifiers in Record Types 1 and 5.

Boundary generation requires the extraction of all features 
that have different left and right geographic codes.  The 
placement of the complete chains into a travel or polygon 
ring sequence requires a procedure to match the end of one 
complete chain to the beginning or end of the next complete 
chain.  Note that the complete chains will probably not 
have the same "to-from" or "start-end" orientation down the 
length of the street or boundary.  Therefore, the procedure 
must reverse the order of the nodes and shape points that 
form some complete chains to achieve a correct/consistent 
sequence of nodes and shape points.  Since the nodes that 
identify the ends of the complete chains do not have an 
identification number, the procedure will have to match the 
nodes based on the latitude and longitude coordinates.  The 
procedure might facilitate the match by combining the 
coordinates into a single peano key code composed of the 
alternating latitude and longitude digits.  Sorting the 
nodes using the peano key clusters nodes that are spatially 
close together.



Polygons

Overview of Polygon Features

Description

The TIGER/Line(TM) files contain identification and 
geographic codes for each GT-polygon in the Census TIGER 
data base.  These GT-polygons are the smallest areas 
identified in the TIGER/Line(TM) files.  Geographic 
entities and area landmarks have specific identification 
codes and form more complex polygons.  The TIGER/Line(TM) 
files link these features to GT-polygons, but do not 
identify the more complex polygons directly.

GT-polygons are building blocks that form features.  They 
are not features and therefor do not have their own feature 
name or CFCC.  However, they can belong to many area 
landmark features each with   its own feature name and 
CFCC.

GT-polygons have unique GT-polygon identification codes 
(CENID   and POLYID); a set of geographic entity codes 
associated with the   GT-polygon and an internal point 
location.  Refer to Chapter 2 for more information about 
the GT-polygon identification codes.  Chapter 4 inventories 
the geographic entities in the TIGER/Line(TM) file and 
lists the record type location.

Information and record linkage keys for GT-polygons are 
distributed over several record types:

  *  Record Type P provides the GT-polygon internal point 
     location.
  *  Record Type A describes the 1990 census geographic 
     entity codes.
  *  Record Type F contains GT-polygons with geographic 
     code corrections.
  *  Record Type G contains GT-polygons with current 
     changes to the geographic codes.
  *  Record Type 8 Links GT-polygons to area landmarks.
  *  Record Type I links GT-polygons to complete chains.

Every GT-polygon has a corresponding Record Type A and P.  
Each version of the TIGER/Line(TM) files will have a 
single, unique set of   GT-polygons.  The GT-polygons in 
Record Types F and G are a subset of the GT-polygons 
identified in Record Types A and P and appear on an as 
needed basis.  The CENID and POLYID identification codes 
link records together, but are not permanent GT-polygon 
identification codes.  Record Type G will identify the 
Record Type F GT-polygons and codes if the code correction 
reflects current geography.  If the geographic entity codes 
or boundaries have changed since the 1990 corrections, 
Record Type G will contain the new codes for the GT-polygon 
and not those of Record Type F, which remain fixed.

Updates to the Census TIGER data base may include new 
complete chains for streets and boundaries that can create 
new GT-polygons.  The set of GT-polygons is unique to each 
version of the TIGER/Line(TM) files.  The new GT-polygons 
only appear in Record Types F or G when they show a 
geographic entity code change.  Record Types F and G also 
contain GT-polygons that have a code change, but are not 
new polygons created through the addition of a boundary 
complete chain.

Geographic Entity Codes

Identification

Geographic entity codes can appear in Record Types A, F, and 
G associated with a set of polygons, Record Types 1 and 3 as 
an attribute of the complete chain, or both.  See the 
description of Record Types A, F, and G in   Chapter 6.  For 
a list of data fields available for a specific geographic 
entity, see Chapter 4.

Internal Points

Identification

The internal point is a point location within each GT-
polygon that is unique to that GT-polygon.  The 
TIGER/Line(TM) files exclude the internal points from the 
node-complete chain-polygon-topology; do not confuse the 
internal point with a centroid.  Unlike true centroids, the 
internal points always fall within the GT-polygon or on the 
GT-polygon boundary.

Some of the GT-polygons (approximately 400 nationwide) are 
so small that the internal point given may be identical to 
a point on one of the lines bounding the GT-polygon or 
identical to one of the nodes.  Depending upon the 
precision of a particular software or hardware system, the 
data user may find the internal point outside the correct   
GT-polygon or find that a GT-polygon may contain two 
internal points.

Changes to the shape and location of complete chains forming 
polygon boundaries will change the polygon interior point 
coordinates even though the topology of the polygon remains 
the same.  Such changes complicate the matching of polygons 
from different versions of the TIGER/Line(TM) files using 
interior point coordinates.

Coordinate Notation

Coordinates are expressed in standard FIPS notation.  See 
the section on Complete Chains, Coordinates for Nodes and 
Shape Points in Chapter 3.


Record Locations:  GT-Polygon Internal Point Coordinates

   RT     Field Name        Description

    P      POLYLONG         Internal point longitude
    P      POLYLAT          Internal point latitude

Values:  Coordinates

All internal points have non-zero coordinates within the 
range specified above.  See the section on Complete Chains, 
Coordinates for Nodes and Shape Points in Chapter 3.

Record Linkages

Description

The topological network of complete chains divide up the 
surface area into all of the GT-polygons in the 
TIGER/Line(TM) files.  There will be a one-to-one 
relationship between the GT-polygons constructed from 
Record Types 1 and 2 and those appearing in Record Type 
P.

In constructing GT-polygons from Record Types 1 and 2, 
users are cautioned to be sure their software has the 
necessary coordinate precision and does not "snap" 
complete chains that are close together.

Record Type I provides a direct link from each complete chain 
in the TIGER/Line(TM) file to its adjoining GT-polygons.  It 
contains both TLID and the polygon identification codes for 
each side of the   GT-polygon.  Record Type I facilitates the 
transfer of polygon geographic codes to the complete chain, 
but also provides the link back from polygon to complete 
chain.  In this case, finding all complete chains associated 
with a GT-polygon is more difficult because a procedure will 
need to search every Record Type I record for all instances 
where a CENID and POLYID appear on either the left or right 
side of a complete chain.

Area landmarks also must link to the GT-polygons in order to 
establish their geographic location.  Record Type 8 provides 
the link from GT-polygon to area landmark.  See the section 
on Area Landmarks below.



Landmark Features 

Overview of Landmark Features

Description

The Census Bureau includes landmarks in the Census TIGER data 
base to locate special features and for map orientation.  
Some of the more common landmark types include airports, 
cemeteries, parks, and educational facilities.

The Census Bureau added landmark features on an as needed 
basis and made no attempt to ensure that all instances of a 
particular feature were included.  The absence of a landmark 
does not mean that the living quarters, e.g., hospitals and 
group quarters associated with the landmark were excluded 
from the 1990 enumeration.  The address list used for the 
census was maintained apart from the landmark data.

A landmark can be either a point, line, or area type.  In 
some cases, the Census TIGER data base permits a choice of 
types.  For instance, an airport or airfield might appear 
as a point, line, or area; the approach depends on the size 
of the feature and the depiction of the feature in the 
source document.

Line features such as airfields could appear as one or more 
complete chains and as such are not identified in the 
landmark record types described below.  See the section on 
Point, Line, and Area Landmark CFCC's in Chapter 3 to 
identify the possible codes that could appear as complete 
chains.

In addition to landmark data, the TIGER/Line(TM) files 
contain the CFCC's and names for bodies of water including 
ponds, lakes, oceans, and the area covered by large streams 
depicted as double line drainage.  Note that these water 
areas have block numbers ending in "99" with some 
exceptions.

Landmark and water features can overlap.  The most common 
situation is a park or other special land use feature that 
includes a lake or pond.  In this case, the GT-polygon 
covered by the lake or pond belongs to a water feature 
landmark and a park landmark feature.  Other kinds of 
landmarks can overlap as well.  Area landmarks can contain 
point landmarks; these are not linked in the TIGER/Line(TM) 
files.

Record Type 7 contains the water area labels, and area and 
point landmarks in the Census TIGER data base.  During the 
extraction of this data, the Census Bureau assigned a 
temporary LAND to each landmark record.  Record Type 8 uses 
the LAND to link the area landmark records in Record Type 7 
to the GT-polygons.  Record Type 7 and Record Type 8 exist 
only when the county file identifies landmark features or 
uses water feature labels.

Point, Line, and Area Landmark CFCC's

Identification

All landmarks have a CFCC.  In the Census TIGER data base the 
CFCC's of the complete chains forming the polygon boundary 
are independent of the CFCC's assigned to the area landmark 
or water feature filling the polygon.

Record Locations:  Landmark CFCC's

   RT     Field Name        Description

    7       CFCC            Code assigned to point and area 
                            landmarks

Codes:  Landmark CFCC's

  CFCC  Description                         Point Line Area

  D00   Landmark feature, classification
        unknown, or not elsewhere classified   P    L    A

  D10   Military installation                  P         A

  D20   Multi-household and transient 
        quarters                               P         A
  D21   Apartment building or complex          P         A
  D22   Rooming or boarding house              P
  D23   Trailer court or mobile home park      P         A
  D24   Marina                                 P         A
  D25   Crew of vessel                                   A
  D26   Housing facility for workers           P         A
  D27   Hotel, motel, resort, spa, YMCA, 
        or YWCA                                P         A
  D28   Campground                             P         A
  D29   Shelter or mission                     P         A

  D30   Custodial facility                     P         A
  D31   Hospital                               P         A
  D32   Halfway house                          P
  D33   Nursing home, retirement home, 
        or home for the aged                   P         A
  D34   County home or poor farm               P         A
  D35   Orphanage                              P         A
  D36   Jail or detention center               P         A
  D37   Federal penitentiary, state prison, 
        or prison farm                         P         A
  D40   Educational or religious institution   P         A
  D41   Sorority or fraternity                 P
  D42   Convent or monastery                   P         A
  D43   Educational institution                P         A
  D44   Religious institution                  P         A

  D50   Transportation terminal                P    L    A
  D51   Airport or airfield                    P    L    A
  D52   Train station                          P         A
  D53   Bus terminal                           P         A
  D54   Marine terminal                        P         A
  D55   Seaplane anchorage                     P         A

  D60   Employment center                      P         A
  D61   Shopping center or major retail center P         A
  D62   Industrial building or industrial park P         A
  D63   Office building or office park         P         A
  D64   Amusement center                       P         A
  D65   Government center                      P         A
  D66   Other employment center                P         A

  D70   Tower                                  P
  D71   Lookout tower                          P

  D80   Open space                             P         A
  D81   Golf course                            P         A
  D82   Cemetery                               P         A
  D83   National park or forest                P         A
  D84   Other federal land                     P         A
  D85   State or local park or forest          P         A

  D90   Special purpose landmark               P         A
  D91   Post office box ZIP Code(R)            P         A

  H00   Water feature, classification  
        unknown, or not elsewhere classified   P    L    A
  H10   Stream                                      L    A
  H11   Perennial stream                            L    A
  H12   Intermittent stream or wash                 L    A
  H13   Braided stream                              L    A

  H20   Canal, ditch, or aqueduct                   L    A
  H21   Perennial canal, ditch, or aqueduct         L    A
  H22   Intermittent canal, ditch, or aqueduct      L    A
  H30   Lake or pond                                     A
  H31   Perennial lake or pond                           A
  H32   Intermittent lake or pond                        A
  H40   Reservoir                                        A
  H41   Perennial reservoir                              A
  H42   Intermittent reservoir                           A
  H50   Bay, estuary gulf, sound, sea, or ocean          A
  H51   Bay, estuary gulf, or sound                      A
  H53   Sea, or ocean                                    A

  H60   Gravel pit or quarry filled with water           A

Landmark Feature Name

Identification

The TIGER/Line(TM) files contain an optional 30-character 
text string used to identify the proper name of the feature 
or water area label.  The text string includes upper and 
lower case characters.  The feature name may carry an 
imbedded feature type (e.g., River, Military Reservation, 
Garden, Park, and Lake).  The Census Bureau has not 
standardized or edited the feature types or names in the 
Census TIGER data base.

The Census Bureau does not guarantee that the landmarks or 
water area labels are consistently identified in the 
TIGER/Line(TM) files.  Area landmarks added to the Census 
TIGER data base in different update actions with the same 
name and CFCC will produce separate landmark records in the 
TIGER/Line(TM) files.  The landmark records may contain 
variant spellings of the feature name or different CFCC's 
even though they refer to the same feature.  These 
differences could result in the fragmentation of a large 
landmark; for instance, part of a large military base could 
have the name Fort James while another part could have the 
name Fort James Military Reservation.  Because area landmarks 
can overlap, it is possible, though not likely, that one 
polygon can belong to both Fort James and Fort James Military 
Reservation.

Area landmarks and water area labels can have alternate 
names.  Each feature name will appear as a separate record 
in Record Type 7, but each record will have the same LAND.  
Record Type 7 records with the same LAND will belong to the 
same landmark or water area label.  Each unique combination 
of primary and alternate names becomes a separate landmark 
record even though the primary name and CFCC's match 
adjoining landmark features.

Record Locations:  Landmark Feature

   RT     Field Name        Description

    7       LANAME          Water area label, and point and
                            area landmark name.


Codes:  Landmark Feature Names

The LANAME field may include any ASCII text string.  The 
field can be blank where the feature is unnamed.

Point Landmark Locations

Identification

The TIGER/Line(TM) files identify the location of point 
landmarks with a single point.  The presence of coordinate 
data in Record Type 7 distinguishes point landmarks from 
area landmarks which have blank coordinate fields.

Coordinates

Coordinates are expressed in standard FIPS notation.  See 
the section on Complete Chains, Coordinates for Nodes and 
Shape Points in Chapter 3 for additional information.

Record Locations:  Point Landmark Location Point Coordinates

   RT     Field Name        Description

    7      LALONG           Location point longitude
    7      LALAT            Location point latitude

Values:  Coordinates

All point landmarks have non-zero coordinates within the 
range specified above.  The coordinate fields for area 
landmarks are blank filled.

Area Landmark Locations

Identification

To find the locations of area landmarks, link the basic 
landmark description in Record Type 7 to all of the 
elementary polygons that belong to the landmark.  Record 
Type 8 serves as a bridge between these two record types.  
The TIGER/Line(TM) files provides a Record Type 8 record 
for each polygon linked to a specific landmark.  Polygons 
belonging to multiple landmarks appear once for each 
landmark.  The TIGER/Line(TM) files uses the LAND and the 
polygon identification codes (CENID and POLYID) to actually 
make the link.  See Chapter 2 for a description of the 
LAND, CENID, and POLYID codes and fields.  Locate the 
polygons for an area landmark by searching Record Type 8 
for all of the CENID's and POLYID's with the specified 
LAND.  Record Type 8 is in LAND sort sequence.

Once the polygons are linked to the area landmark, use 
Record Type I to locate the complete chains that form the 
landmark's polygon boundaries.  Note that Record Type I 
contains a record for all complete chains and identifies the 
polygons located on either side of the complete chains.  The 
search procedure must search all instances of Record Type I 
and evaluate the left- and right-side polygon identifiers 
for a possible match.  Data users may need to eliminate 
complete chains that are internal to the polygon and 
landmark depending on the application.