A geographic variant designates a version of a geographic entity based on the date that the entity’s boundaries are intended to represent. Geographic variants only apply to specific types of geographic entities.

For most geographic entities, like states and counties, the Census Bureau updates their boundaries once a year. Normally, census and survey data tabulated in 2023, for example, describe geographic areas as they were defined in the Census Bureau database on January 1, 2023. For most geographic areas, there is only one boundary definition used to tabulate survey data for a given year.

Some geographic entities are handled in a different way. For these areas, the Census Bureau may tabulate the same survey data for different variations of the same geographic area. Additionally, different surveys published for the same year may use different variations of the geographic area in the data tabulations. In those cases, the Census Bureau uses a geographic variant, in addition to the survey name and data year, to help users link survey data to the geographic area boundaries they represent.

The following geographic areas require a geographic variant in addition to a data year to uniquely identify their corresponding survey data.

Congressional districts
State legislative districts
Core based statistical areas (metropolitan and micropolitan statistical areas), metropolitan divisions, and combined statistical areas
Urban areas
Public use microdata areas
ZIP Code tabulation areas

For example, a single set of data, like the 2020 Decennial Census data, may include data tabulated for both the 116th congressional districts, which were in place the year the census was taken in 2020, and the 118th congressional districts, whose geographic boundaries were not defined until after the census was taken.

The same variant code must be used for geographic areas at the pertinent summary level and all subordinate (child) summary level geographies from the same time period. Superior (parent) geographies do not require geographic variant codes, such as in the case of states for congressional districts.

Geographic Variant Code Group Assignations

Geographic Variant Code Range: 00

Type/Highest-level Summary Level: Standard variant

Description:

Default: no geographic variant specified.

Geographic Variant Code Range: 01-59

Type/Highest-level Summary Level: State-Congressional District (500)

Description:

Add 100 to the geographic variant code to get the number for the session of the U.S. Congress.

The code range supports the 101st Congress through the 159th Congress (through the election in 2104, session in 2105-2106).

Geographic variant code values and the corresponding congressional district session number for historical tabulations through the years in the 2020 Census cycle are:

06 — 106th Congress (Election in 1998, session in 1999-2000)
07 — 107th Congress (Election in 2000, session in 2001-2002)
08 — 108th Congress (Election in 2002, session in 2003-2004)
09 — 109th Congress (Election in 2004, session in 2005-2006)
10 — 110th Congress (Election in 2006, session in 2007-2008)
11 — 111th Congress (Election in 2008, session in 2009-2010)
12 — 112th Congress (Election in 2010, session in 2011-2012)
13 — 113th Congress (Election in 2012, session in 2013-2014)
14 — 114th Congress (Election in 2014, session in 2015-2016)
15 — 115th Congress (Election in 2016, session in 2017-2018)
16 — 116th Congress (Election in 2018, session in 2019-2020)
17 — 117th Congress (Election in 2020, session in 2021-2022)
18 — 118th Congress (Election in 2022, session in 2023-2024)
19 — 119th Congress (Election in 2024, session in 2025-2026)
20 — 120th Congress (Election in 2026, session in 2027-2028)
21 — 121st Congress (Election in 2028, session in 2029-2030)

Geographic Variant Code Range: Ux

Type/Highest-level Summary Level: State-State Legislative District (Upper Chamber) (610)

Description:

Geographic variant code values should be consistent with the “Ux” pattern.

Typically, the variant for state legislative districts changes in sync with the congressional districts on a two-year cycle (elections in even-numbered years). For states with state legislative district elections in odd-numbered years, the variant corresponds to the election and session one year earlier.

Geographic variant code values and the corresponding state legislative district election and session years for historical tabulations through the years in the 2020 Census cycle are:

U0 — Election in 1999 or 2000, session in 2000-2001 or 2001-2002
U1 — Election in 2005 or 2006, session in 2006-2007 or 2007-2008
U2 — Election in 2009 or 2010, session in 2010-2011 or 2011-2012
U3 — Election in 2011 or 2012, session in 2012-2013 or 2013-2014
U4 — Election in 2013 or 2014, session in 2014-2015 or 2015-2016
U5 — Election in 2015 or 2016, session in 2016-2017 or 2017-2018
U6 — Election in 2017 or 2018, session in 2018-2019 or 2019-2020
U7 — Election in 2019 or 2020, session in 2020-2021 or 2021-2022
U8 — Election in 2021 or 2022, session in 2022-2023 or 2023-2024
U9 — Election in 2023 or 2024, session in 2024-2025 or 2025-2026
UA — Election in 2025 or 2026, session in 2026-2027 or 2027-2028
UB — Election in 2027 or 2028, session in 2028-2029 or 2029-2030

Subsequent geographic variant code values are expected to follow the pattern: UC, UD, … UZ (all capital letters), followed by Ua, Ub, … Uz (second letter lower-case). Code UZ would correspond to the election in 2075 or 2076, and code Uz would correspond to the election in 2127 or 2128.

Geographic Variant Code Range: Lx

Type/Highest-level Summary Level: State-State Legislative District (Lower Chamber) (620)

Description:

Geographic variant code values should be consistent with the “Lx” pattern.

Geographic variant code values and the corresponding state legislative district election and session years for historical tabulations through the years in the 2020 Census cycle are:

L0 — Election in 1999 or 2000, session in 2000-2001 or 2001-2002
L1 — Election in 2005 or 2006, session in 2006-2007 or 2007-2008
L2 — Election in 2009 or 2010, session in 2010-2011 or 2011-2012
L3 — Election in 2011 or 2012, session in 2012-2013 or 2013-2014
L4 — Election in 2013 or 2014, session in 2014-2015 or 2015-2016
L5 — Election in 2015 or 2016, session in 2016-2017 or 2017-2018
L6 — Election in 2017 or 2018, session in 2018-2019 or 2019-2020
L7 — Election in 2019 or 2020, session in 2020-2021 or 2021-2022
L8 — Election in 2021 or 2022, session in 2022-2023 or 2023-2024
L9 — Election in 2023 or 2024, session in 2024-2025 or 2025-2026
LA — Election in 2025 or 2026, session in 2026-2027 or 2027-2028
LB — Election in 2027 or 2028, session in 2028-2029 or 2029-2030

Subsequent geographic variant code values are expected to follow the pattern: LC, LD, … LZ (all capital letters), followed by La, Lb, … Lz (second letter lower-case). Code LZ would correspond to the election in 2075 or 2076, and code Lz would correspond to the election in 2127 or 2128.

Geographic Variant Code Range: Mx

Type/Highest-level Summary Level: Metropolitan Statistical Area/Micropolitan Statistical Area (310), Combined Statistical Area (330), Combined New England City and Town Area (335)¹, New England City and Town Area (350)¹

Description:

Geographic variant code values should be consistent with the “Mx” pattern.

A new geographic variant code is introduced with new Office of Management and Budget (OMB) delineations of metropolitan and micropolitan statistical areas, collectively referred to as core based statistical areas (CBSAs). A geographic variant code value of M6 is associated with the March 6, 2020, OMB Bulletin No. 20-01, "Revised Delineations of Metropolitan Statistical Areas, Micropolitan Statistical Areas, and Combined Statistical Areas, and Guidance on Uses of the Delineations of These Areas." The delineations presented in this OMB Bulletin are used in the 2020 Census data products. A geographic variant code value of M7 is associated with the July 21, 2023, OMB Bulletin No. 23-01.

Geographic variant code values and the corresponding OMB delineations of metropolitan and micropolitan statistical areas for historical tabulations through the years in the 2020 Census cycle are:

M1 — OMB Bulletin No. 10-02, December 1, 2009
M2 — OMB Bulletin No. 13-01, February 28, 2013
M3 — OMB Bulletin No. 15-01, July 15, 2015
M4 — OMB Bulletin No. 17-01, August 15, 2017
M5 — OMB Bulletin No. 18-04, September 14, 2018
M6 — OMB Bulletin No. 20-01, March 6, 2020
M7 — OMB Bulletin No. 23-01, July 21, 2023

Subsequent geographic variant code values are expected to follow the pattern: M8, M9, followed by MA, MB, … MZ (all capital letters), followed by Ma, Mb, … Mz (second letter lower-case).

¹ OMB no longer defines New England city and town areas and related areas. They last appear in tabulations in the 2022 data year.

Geographic Variant Code Range: Cx

Type/Highest-level Summary Level: Urban Area (400)

Description:

Geographic variant code values should be consistent with the “Cx” pattern.

All summary level 400 geographies and their child summary level geographies (if any) used in 2010 tabulation or later should have a Cx variant code. Code C1 is for the 2010 urban-rural classification. The 2000 Census keeps its current variant code of 00.

Tabulations in 2020 may cover both 2010 and 2020 definitions in different datasets. 2020 American Community Survey (ACS) tabulations use the 2010 urban-rural classification and code C1. 2020 Census tabulations are based on the 2020 urban-rural classification and use code C2.

This pattern is expected in future classifications of urban and rural. For example, 2030 ACS tabulations will use the 2020 urban-rural classification and code C2. When the Census Bureau classifies urban and rural based on 2030 Census data, the 2030 Census tabulations will use code C3.

Geographic variant code values and the corresponding urban-rural classification from 2010-2030 are:

C0 — 2000 Census urban-rural classification²
C1 — 2010 Census urban-rural classification
C2 — 2020 Census urban-rural classification
C3 — 2030 Census urban-rural classification

Future geographic variant code values are expected to follow the pattern: C4, C5, … C9, followed by CA, CB, … CZ (all capital letters), followed by Ca, Cb, … Cz (second letter lower-case).

Beginning with the 2020 urban-rural classification, summary levels with geographic components 01 (Urban) and 43 (Rural) use the geographic variant code associated with their urban-rural vintage. Summary levels that contain CBSAs and have geographic components with an urban-rural characteristic use the geographic variant code associated with their CBSA vintage.

² The C0 geographic variant code is used only in 2010 and 2011 ACS data tabulations to reference the 2000 Census urban-rural classification. 2000 Census data uses geographic variant code 00.

Geographic Variant Code Range: Zx

Type/Highest-level Summary Level: 5-digit ZIP Code Tabulation Area (ZCTA) (860)

Description:

Geographic variant code values should be consistent with the “Zx” pattern.

All summary level 860 geographies and their child summary level geographies (if any) used in 2020 tabulation or later should have a Zx variant code. Code Z2 is for the 2020 ZCTA delineation. The 2000 and 2010 censuses keep their current variant code of 00.

Tabulations in 2020 may cover both 2010 and 2020 definitions in different datasets. 2020 ACS tabulations use the 2010 ZCTA definitions and code 00. 2020 Census tabulations based on the 2020 ZCTA delineation use code Z2.

This pattern is expected in future ZCTA delineations. For example, the 2030 ACS tabulations will use the 2020 ZCTA definitions and code Z2. When the Census Bureau redefines ZCTAs based on 2030 Census data, the 2030 Census tabulations will use code Z3.

Geographic variant code values and the corresponding ZCTA delineation from 2020-2030 are:

Z2 — 2020 Census delineation
Z3 — 2030 Census delineation

Future geographic variant code values are expected to follow the pattern: Z4, Z5, … Z9, followed by ZA, ZB, … ZZ (all capital letters), followed by Za, Zb, … Zz (second letter lower-case).

Geographic Variant Code Range: Px

Type/Highest-level Summary Level: State-Public Use Microdata Area (PUMA) (795)

Description:

Geographic variant code values should be consistent with the “Px” pattern.

All summary level 795 geographies and their child summary level geographies (if any) used in 2020 tabulation or later should have a Px variant code. Code P2 is for the 2020 PUMA delineation. The 2000 and 2010 censuses keep their current variant code of 00.

Geographic variant code values and the corresponding PUMA delineation from 2020-2030 are:

P2 — 2020 PUMA delineation
P3 — 2030 PUMA delineation

Future geographic variant code values are expected to follow the pattern: P4, P5, … P9, followed by PA, PB, … PZ (all capital letters), followed by Pa, Pb, … Pz (second letter lower-case).

Page Last Revised - August 2, 2024

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