The 2020 Standards for Delineating 

Core Based Statistical Areas

Paul Mackun, Ph.D.

Population Division 

U.S. Census Bureau

This presentation is released to inform interested parties of ongoing research and to encourage discussion of work in progress. Any opinions and conclusions expressed herein are those of the author and do not reflect the views of the U.S. Census Bureau.
Core Based Statistical Area (CBSA) Classification

A CBSA consists of the central county or counties (or equivalents) 

associated with at least one core of 10,000 population or greater, plus 

adjacent counties having a high degree of social and economic 

integration with the central county or counties as measured by 

commuting ties.

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Core Based Statistical Areas Population in a Core

Metropolitan Statistical Area 50,000 or more

Micropolitan Statistical Area 10,000 to 49,999

Territory not included in a CBSA is designated as Outside Core 

Based Statistical Areas
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Representative Metropolitan and Micropolitan 

Statistical Areas with Urban Areas
Commuting Thresholds

A county qualifies as an outlying county if:

• At least 25 percent of the employed residents of the county work 

in the CBSA’s central county or counties, or

• At least 25 percent of the employment in the county is accounted 

for by workers residing in the CBSA’s central county or counties.

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Adjacent CBSAs merge to form a single CBSA when the 

central county or counties of one area qualify as outlying to 

the central county or counties of another. 
Metropolitan Divisions

• Metropolitan statistical areas containing a core with a 

population of 2.5 million or greater may be subdivided to 

form metropolitan divisions.

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Combined Statistical Areas

A combination reflects social and economic ties between 

adjacent CBSAs as measured by commuting that are lower 

than ties required for merging (that is, for becoming a single 

metropolitan or micropolitan statistical area).

Adjacent CBSAs may form a combined statistical area 

(CSA) based on commuting ties between whole areas.

CBSAs that combine also retain separate identities as 

metropolitan statistical areas or micropolitan statistical 

areas within the larger CSA.

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Counts of Metropolitan and Micropolitan Statistical Areas

• 392 metropolitan statistical areas (384 in the United States and 8 in 

Puerto Rico)

• 547 micropolitan statistical areas (543 in the United States and 4 in 

Puerto Rico)
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Counts of CSAs

• 175 CSAs (172 in the United States and 3 in Puerto Rico)

• 551 component metropolitan and/or micropolitan statistical areas 

(541 in the United States and 10 in Puerto Rico)

• 270 component metropolitan statistical areas (263 in the United 

States and 7 in Puerto Rico)

• 281 component micropolitan statistical areas (278 in the United 

States and 3 in Puerto Rico)
Core 

Based 

Statistical 

Areas 

(CBSAs)

United States and Puerto Rico

Counties

Outside Core Based 

Statistical Areas

Core Based Statistical Areas:

Metropolitan Micropolitan 

Statistical Areas Statistical Areas

Metropolitan

Divisions

Combined

Statistical 

Areas (CSAs)

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Standards Review

• Review of the 2010 standards

• Recommended changes to the 2010 standards and final 

2020 standards

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Recommendations accepted by OMB

OMB accepted the Metropolitan and Micropolitan Statistical 

Area Standards Review Committee recommendations that: 

1. OMB discontinue delineation of New England city and town areas 

(NECTAs), NECTA divisions, and combined NECTAs. 

2. OMB launch a research effort into delineating territorially 

exhaustive areas.

3. OMB incorporate the results of the decade’s first annual update 

review into the results of the decade’s decennial census-based 

update.

4. OMB provide an update schedule. 

5. OMB continue use of American Community Survey commuting 

data to measure intercounty connectivity. 

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Guidance on General Uses

• The classification provides a nationally consistent set of 

delineations for collecting, tabulating, and publishing 

federal statistics for geographic areas.

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Nonstatistical Uses of Statistical Areas

• In reviewing and revising these areas, OMB does not take into 

account, or attempt to anticipate, any public or private sector 

nonstatistical uses of the delineations.

• These areas are not designed for the purpose of serving as a 

general-purpose geographic framework applicable for use in 

program administration or funding formulas. 

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More Information

• More information on metropolitan and micropolitan 

statistical areas is available on the Census Bureau’s 

metro/micro webpage, at: www.census.gov/programssurveys/metro-micro.html

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Contact Information

paul.j.mackun@census.gov

301-763-6047

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