These files show the relationships (comparability) for the same type of geography over different periods of time (e.g. the relationship between places in 2010 and places in 2000).

The county subdivision relationship file provides a simple relationship between each 2010 Census county subdivision and its comparable Census 2000 county subdivision (if comparability exists) with an additional comments section to describe more detailed changes.  For the vast majority of records, there is a one-to-one relationship between a 2010 Census county subdivision and a Census 2000 county subdivision, although names and codes may have changed between censuses.  Where a 2010 Census record has no comparable Census 2000 county subdivision information, it is the result of new subdivisions being created from existing areas or the 2010 Census county subdivisions have changed so dramatically as to preclude any relationship.  The NOTES column provides additional information if required.

Relationships for governmental county subdivisions is based on continuing governmental status although there may have been substantial boundary changes or other changes that modified the boundaries.  For nonfunctioning legal county subdivisions and statistical entities, relationships are based on the entity still being defined for its "core" area.  In some states, most notably Louisiana, Maryland, and Mississippi, county governments completely re-drew the county subdivision boundaries; in these cases the NOTES column uses the term "Redistricted" to indicate a lack of any relationship. Tennessee changed its county subdivisions from statistical census county divisions (CCDs) to legal County Commissioner Districts and there is no comparability for any Tennessee county subdivisions.

All relationships are based on a preliminary compilation and review of data; some changes may appear in later products.  The Census Bureau, however, believes this file to be overwhelmingly accurate, and is releasing this preliminary version in response to requests for information about county subdivision relationships.  The final version of this file is expected to be released in the first quarter of 2012.

The place relationship file provides a simple relationship between each 2010 place (incorporated place, census designated place [CDP], or consolidated city) and its comparable 2000 place with an additional comments section to describe more detailed changes. For the vast majority of records, there is a one-to-one relationship between a 2010 place and a 2000 place, although names and codes may have changed between censuses. Where a 2010 record has no comparable 2000 place information, most of the 2010 places are newly defined from area not in a place, but the Comments column provides additional information if required.

Comparability for incorporated places is based on continuing governmental status; there may have been substantial boundary changes or other changes that modified the boundaries. For CDPs, comparability is based on the CDP still being defined for its "core" area as determined by local participants and through points identified in the Geographic Names Information System developed to support the U.S. Board on Geographic Names as the official repository of domestic geographic names data. As with incorporated places, comparability implies continuity of definition, but the actual area of a CDP may have changed between 2000 and 2010.

The 2010 urban area relationship file describes the relationship between 2010 and Census 2000 urban areas.

These files show the relationship between different types of geography for the same time period (e.g. the relationships between congressional districts and places).

The Census Tract Relationship files provide simple relationships between the 2010 Census Tracts and the specified geographies.

Tract to American Indian Area Relationship File

The 2010 census tract to American Indian area relationship file is provided as a tool for data users interested in understanding which census tracts contain an American Indian area. American Indian areas include Federally recognized Reservations and trust lands, State recognized Reservations, State designated tribal statistical areas (SDTSAs), tribal designated statistical areas (TDSAs), Oklahoma tribal statistical areas (OTSAs), Hawaiian Homelands (HHLs), and Alaska Native village statistical areas (ANVSAs). Census tracts do not necessarily nest within American Indian areas, so the list includes all census tracts that contain any amount of American Indian area. The total area, 2010 population count, and 2010 housing unit count of the intersection between the census tract and American Indian area are provided, as well as the percentage of the census tract covered. The list does not contain all 2010 census tracts. It only contains the census tracts that intersect with an American Indian area. American Indian areas are updated occasionally; however, we do not have plans to create an updated relationship file at this time. The list is accurate as of January 1, 2010.

The tracts represented in the relationship are the standard county-based census tracts. The Census Bureau also offers data by tribal census tract which is an additional layer that nests within Federally recognized Reservations and trust lands. For more information on American Indian areas, please visit our Glossary.

Tract to Military Area Relationship File

The 2010 census tract to military area relationship file is provided as a tool for data users interested in understanding which census tracts contain a military base or outlying area. Census tracts do not necessarily nest within military areas, so the list includes all census tracts that contain any amount of military area. The total area of the intersection between the census tract and military area is provided, as well as the percentage of the census tract covered. The list does not contain all 2010 census tracts. It only contains the census tracts that intersect with a military area. Military areas are updated occasionally; however, we do not have plans to create an updated relationship file at this time. The list is accurate as of October 2012.

Tract to Publice Use Microdata Area (PUMA) Relationship File

The 2010 Census tract to 2010 PUMA relationship file is provided as a tool for data users to identify which census tracts are contained within a PUMA. For the 2010 Census, tracts nest within PUMAs. This file includes all 2010 Census tracts and 2010 PUMAs. The list is accurate as of April 6, 2012.

The Congressional District Relationship files provide simple relationships between the specified Congressional District and other Census 2000 and 2010 Census tabulation geography including American Indian areas, counties, county subdivisions, census tracts, places, school districts, urban/rural population and land area, and ZIP Code Tabulation Areas. The links below provide more information about the relationship files, including format and layouts, as well as a link to the files.

Congressional Districts Relationship Files (State-based)

These tables show the relationships between congressional districts and other geographies. Tables for the 108th through the 110th congressional districts show relationships between the congressional districts and the following (as they existed in Census 2000): counties or county equivalents, incorporated places and census designated places (including consolidated cities), county subdivisions (for 18 states), American Indian areas, census tracts, ZIP Code tabulation areas (ZCTAs), urban and rural population and land area, and school districts. Tables for the 113th congressional districts show relationships between the congressional districts and counties or county equivalents, incorporated places and census designated places (including consolidated cities), county subdivisions (for all states), American Indian areas, census tracts, ZIP Code tabulation areas (ZCTAs), urban and rural population and land area, and school districts, as they existed in Census 2010.

There are no tables for the single member states (Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont, and Wyoming) or for the statistically equivalent areas of non-voting delegates (the District of Columbia, American Samoa, Guam, Puerto Rico, and the U.S. Virgin Islands).

Note: For inter-censal changes to congressional districts, new tables are only generated for states with changes after the initial post-decennial redistricting. No new tables were generated for the 114th Congress, for example, because no states made changes to their 113th Congressional District boundaries.

American Indian Areas by Congressional District

The U.S. Census Bureau tabulates and presents data for American Indian reservations and off-reservation trust lands. This includes the legally defined areas associated with both federally recognized and state-recognized tribes. The Census Bureau also tabulates and presents data for several statistical American Indian areas that are represented in the table. These include Oklahoma Tribal statistical areas, tribal designated statistical areas, and state designated tribal statistical areas (known prior to 2010 as state designated American Indian statistical areas).

A federal American Indian reservation is an area that has been set aside by the United States for the use of one or more federally recognized American Indian tribes. Its boundary is defined by tribal treaty, agreement, executive or secretarial order, federal statute, or judicial determination. The Census Bureau recognizes a federal reservation as territory over which a tribe(s) has primary governmental authority. A state American Indian reservation is an area that a state government has allocated to a tribe recognized by that state, but not by the federal government. American Indian reservations are known as colonies, communities, Indian communities, Indian villages, pueblos, rancherias, ranches, reservations, reserves, and villages. American Indian trust land is an area for which the United States holds title in trust for the benefit of an American Indian tribe or for an individual American Indian. Trust land may be located on or off a reservation; however, the Census Bureau recognizes and tabulates data only for off-reservation trust land. Census data always associates off-reservation trust land with a specific federally recognized reservation and/or tribal government.

A state designated tribal statistical area (SDTSA) is a statistical entity delineated for a state-recognized American Indian tribe that does not have a land base (reservation or off-reservation trust lands). SDTSAs are identified and delineated for the Census Bureau by a state liaison identified by that state’s governor's office. An SDTSA generally encompasses a compact and contiguous area that contains a concentration of people who identify with a state recognized American Indian tribe and in which there is structured or organized tribal activity.

A tribal designated statistical area (TDSA) is a statistical entity delineated for the Census Bureau by a federally recognized American Indian tribe that does not have a federally recognized land base (a reservation or off-reservation trust land). A TDSA generally encompasses a compact and contiguous area that contains a concentration of people who identify with a federally recognized American Indian tribe and in which there is structured or organized tribal activity.

This table lists the American Indian area names alphabetically within each subject state and provides the congressional district code that relates to each area. If an American Indian area extends into other states, the area name is followed by (pt.). If more than one congressional district relates to the American Indian area, each congressional district code is listed, separated by a comma or a hyphen (e.g. 6-9 represents congressional districts 6, 7, 8 and 9).

This file is only available for the 113th Congress.

Congressional Districts by Census Tract

Census tracts are small, relatively permanent statistical subdivisions of a county or statistically equivalent entity delineated by local participants as part of the U.S. Census Bureau's Participant Statistical Areas Program. The U.S. Census Bureau delineated census tracts where no local participant existed or where a local or tribal government declined to participate. The primary purpose of census tracts is to provide a stable set of geographic units for the presentation of decennial census data.

Census tracts are identified by a four-digit basic number and may have a two-digit numeric suffix; for example, 6059.02. The decimal point separating the four-digit basic tract number from the two-digit suffix is shown in printed reports and on census maps. In computer-readable files, the decimal point is implied. Many census tracts do not have a suffix; in such cases, the tract number is right justified and zero-filled. Leading zeros in a census tract number (for example, 002502) are shown only in computer-readable files.

Census tract numbers range from 1 to 9999 and are unique within a county or statistically equivalent entity. 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 was 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 was not used as a census tract code in the 2010 Census.

This table lists alphabetically each county name and 3-digit Federal Information Processing System (FIPS) code and the census tract codes within that county. It then provides the congressional district that relates to each census tract. If an entire county is within one congressional district, the table will have the note "All Census Tracts." If more than one congressional district relates to a census tract, each district is listed, separated by a comma or a hyphen (e.g. 6-9 represents congressional districts 6, 7, 8 and 9).

Counties by Congressional Districts

Counties and county equivalents (e.g. parishes and boroughs) are the primary legal divisions of most states. Most counties are functioning governmental units, whose powers and functions vary from state to state. In four states (Maryland, Missouri, Nevada, and Virginia), one or more cities are independent of any county and thus constitute primary divisions of their states. The Census Bureau refers to these places as "independent cities" and treats them as the equivalents of counties for data purposes.

This table lists each congressional district in the state and provides the county name for each county that is contained within the district. A county that is only partially contained within a district is indicated by "(pt.)" following the county name.

Congressional Districts by Counties

Counties and county equivalents (e.g. parishes and boroughs) are the primary legal divisions of most states. Most counties are functioning governmental units, whose powers and functions vary from state to state. In four states (Maryland, Missouri, Nevada, and Virginia), one or more cities are independent of any county and thus constitute primary divisions of their states. The Census Bureau refers to these places as "independent cities" and treats them as the equivalents of counties for data purposes.

This table lists each county name alphabetically within the state and provides the congressional district code that relates to it. If a county relates to more than one congressional district, each district is listed, separated by a comma or a hyphen (e.g. 6-9 represents congressional districts 6,7,8, and 9).

Congressional Districts by County Subdivisions

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. Minor civil divisions (MCDs) are the primary governmental or administrative divisions of a county in 29 states (parishes in Louisiana) and 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. 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 within the 21 states where there are no legally established MCDs.

This table lists each county subdivision name alphabetically within the state and provides the county name and congressional district that relate to each county subdivision. If a county subdivision relates to more than one congressional district, each district is listed, separated by a comma or a hyphen (e.g. 6-9 represents congressional districts 6, 7, 8 and 9).

Note: Tables for all congressional sessions prior to the 113th include only the MCDs in 18 states. The tables for the 113th Congress include county subdivisions in all states.

Congressional Districts by Places

Incorporated places recognized by the Census Bureau for Census 2010 data are those reported to the U.S. Census Bureau as legally in existence on January 1, 2010--under the laws of their respective states--as cities, boroughs, municipalities, towns, and villages, with the following exceptions: the towns in the New England states, New York, and Wisconsin, and the boroughs in New York which are recognized as minor civil divisions for decennial census purposes. Incorporated places recognized by the Census Bureau for Census 2000 were those reported to the Census Bureau as legally in existence on January 1, 2000. Incorporated places can cross both county and MCD boundaries.

Census designated places (CDPs) are delineated for each decennial census as the statistical counterparts of incorporated places. CDPs are delineated to provide census data for concentrations of population, housing, and commercial structures that are identifiable by name but are not within an incorporated place. CDP boundaries are usually defined in cooperation with state, local, and tribal officials. These boundaries, which usually coincide with visible features or the boundary of an adjacent incorporated place or other legal entity, 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.

This table lists each incorporated place and census designated place name alphabetically within the state and provides the county name and congressional district that relate to each place. If a place relates to more than one county, each county name is listed. If a place relates to more than one congressional district, each district is listed, separated by a comma or a hyphen (e.g. 6-9 represents congressional districts 6, 7, 8 and 9).

Congressional Districts by School Districts

School districts are geographic entities within which state, county, or local officials, the Department of Defense, or the Bureau of Indian Affairs provides public educational services for the residents. The U.S. Census Bureau obtains the boundaries and names for school districts from state officials.

This table lists each school district alphabetically by name and provides the congressional district that relates to the area. If more than one congressional district relates to a school district, each congressional district is listed, separated by a comma or a hyphen (e.g. 6-9 represents congressional districts 6, 7, 8 and 9). If there are two different school districts in the same state with the same name, the county name is added in parentheses after the school district name to distinguish them.

Congressional Districts by Urban/Rural Population and Land Area

The Census Bureau classifies 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 of UAs and UCs. Geographic entities, such as congressional districts, metropolitan areas, counties, minor civil divisions (MCDs), and places, often contain both urban and rural territory, population, and housing units.

This table provides the total population for each congressional district and the population of the district that is classified by the Census Bureau as urban and that part classified as rural. It also provides the total land area for the district and the land area that is classified as urban and that part classified as rural. Also included are the percentages of the population and land areas that are urban and rural within the district.

Congressional Districts by ZIP Code Tabulation Areas (ZCTAs)

ZCTAs are generalized area representations of U.S. Postal Service (USPS) ZIP Code service areas. Since ZCTAs are NOT exact representations of the USPS' ZIP Code delivery areas they should not be used for mailing purposes. ZCTAs are distinct from other Census Bureau statistical areas, such as census tracts, because they are computer-delineated based on the location of addresses at the time of the Census rather than manually delineated by local program participants or Census Bureau staff before the census.

This table lists each ZCTA 5-digit code, numerically within the state, and provides the congressional district that relates to each ZCTA. If more than one congressional district relates to a ZCTA, each district is listed, separated

Congressional Districts Relationship Files (Nation-based)

The nation-based comma delimited relationship files contain a separate record for each unique entity code combination. For example, in the Congressional Districts and Counties file, if the county contains two congressional districts, there will be two records in the file for that county; one for each congressional district.

There are no tables for the single member states (Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont, and Wyoming) or for the statistically equivalent areas of non-voting delegates (the District of Columbia, American Samoa, Guam, Puerto Rico, and the U.S. Virgin Islands).

These files contain only geographic reference codes; they do not include entity names. The codes are right justified and zero filled.

Note: For inter-censal changes to congressional districts, new tables are only generated for states with changes after the initial post-decennial redistricting. No new tables were generated for the 114th Congress, for example, because no states made changes to their 113th Congressional District boundaries.

The State Legislative District Relationship files provide simple relationships between the specified state legislative district (upper house or lower house) and 2010 Census tabulation geography including American Indian areas, counties, county subdivisions, census tracts, places, school districts, urban/rural population and land area, and ZIP Code Tabulation Areas. The links below provide more information about the relationship files, including format and layouts, as well as a link to the files.

The 2010 urban area relationship files provide simple relationships between the 2010 urban areas and other 2010 Census tabulation geography: counties, county subdivisions (in states with governmental minor civil divisions only), places (incorporated places and census designated places), metropolitan and micropolitan statistical areas, New England city and town metropolitan and micropolitan statistical areas (NECTAs), and ZIP Code tabulation areas (ZCTAs). A 2010 urban area relationship file also describes the relationship between 2010 and Census 2000 urban areas. From these files, data users may determine which urban areas exist within the other geographies and vice versa. Also see the Congressional District relationship files section above for the 113th Congressional Districts to Urban/Rural Population and Land Area relationship files.

Overview of the Urban Area Relationship Files

The urban area relationship files are nation-based, comma-delimited ASCII files and include all 50 states, the District of Columbia, Puerto Rico, and the Island Areas.

These files represent the full extent of both the urban areas and the related geography. They contain separate records for (a) the territory of intersection between the urban areas and the related geographic entities, (b) the territory within the urban areas but outside the related geographic entities, and (c) the territory outside any urban area but within the related geographic entities.

For example, consider the hypothetical situation where the Fairview urbanized area may overlap part of Pine Grove incorporated place. The urban area to place relationship file will include a record that contains the population, housing count, land area, and total area for the territory of overlap between Fairview and Pine Grove; a record that contains the population, housing count, land area, and total area for the territory within Fairview but outside Pine Grove (if it exists); and a record that contains the population, housing count, land area, and total area for the territory outside Fairview but within Pine Grove (if it exists).

In addition to the population, housing count, land area, and total area for the parts of an urban area and a related geographic entity, each record also includes population, housing count, land area, and total area for the whole urban area and related entity and the percent population, housing count, land area, and total area that the parts represent of the whole.

The 2010 ZIP Code Tabulation Area (ZCTA) Relationship files provide simple relationships between the 2010 ZCTAs and other 2010 Census tabulation geography. From these files, data users may determine which ZCTAs exist within the other geographies and vice versa. Please use the links below to find out more about the 2010 ZCTA Relationship files. Also see the Congressional District relationship files section above for the 113th Congressional Districts to ZCTA relationship files.

Overview of the 2010 ZIP Code Tabulation Area (ZCTA) Relationship Files

The 2010 ZIP Code Tabulation Area (ZCTA) Relationship files provide simple relationships between the 2010 ZCTAs and other 2010 Census tabulation geography: counties, county subdivisions, places (incorporated places and census designated places), census tracts, metropolitan and micropolitan statistical areas, New England city and town areas (NECTAs), and congressional districts. From these files, data users may determine which ZCTAs exist within the other geographies and vice versa. 

The ZCTA relationship files are nation-based comma-delimited ASCII files and include all 50 states, the District of Columbia, and Puerto Rico.

These files represent intersections of geography only.  For instance, for the ZCTA to place relationship file, a unique combination of ZCTA and place FIPS code must exist for a record to be included in the file. Areas where the Census Bureau has delineated a ZCTA, but no place exists, are considered remainder records and are not included in this file. Situations where no ZCTA exists or where there is neither a ZCTA nor a place are also excluded from this file. The same logic applies to all other relationship files. However, data users should be aware that the totals given for the ZCTA or the geographic entity are full totals as published for the 2010 Census, therefore, data users should note that summing the part record totals may not match the totals for the ZCTAs and/or the related entities.