2009 BAS Map Files Description Page

The U.S. Census Bureau conducts the Boundary and Annexation Survey (BAS) annually to collect information about selected legally defined geographic areas.  The BAS is used to update information about the legal boundaries and names of governmental units in the United States.  The 2009 BAS maps display the updated legal boundaries and names valid thru January 1, 2008, for all governmental units that participated in the 2008 BAS.  The BAS maps are created for the following entity types:

• American Indian Areas (AIAs):  AIAs include federally recognized American Indian Reservations, American Indian off-reservation trust land, and American Indian tribal subdivision boundaries.  AIA maps can be found by opening the American Indian Areas link on the main page.

The file naming convention for AIAs is as follows:  BAS09R4<st><tribal code><tribal area code>_<xxx>.pdf,
where <st> represents the two digit state code, <tribal code> represents the four digit tribal code, <tribal area code> represents the four digit tribal area code, and <xxx> represents the mapsheet number.  An example of an AIA file name is:  BAS09R49900090495_001.pdf.

• Consolidated Cities:  A type of incorporated place that contains one or more other incorporated places that continue to function as separate governmental units within a consolidated government. Consolidated City maps can be found by opening the link to the state of your interest and then opening the link to the list of consolidated cities for that state.

The file naming convention for Consolidated Cities is as follows:  BAS09CC0<st>000<yyyyy>_<xxx>.pdf,
where <st> represents the two digit state code, <yyyyy> represents the five digit Consolidated city fips code, and <xxx> represents the mapsheet number. An example of a Consolidated City file name is:  BAS09CC00900047500_003.pdf

• Counties:  The primary legal division of states except in the states of Alaska and Louisiana.  In Alaska, Census Areas and Boroughs are recognized by the Census Bureau as a county equivalent.  In Louisiana, Parishes are recognized by the Census Bureau as a county equivalent.   In Puerto Rico, the Census Bureau recognizes municipios as the county equivalent.  County maps can be found by opening the link to the state of your interest, and then opening the link to the list of counties in that state.

The file naming convention for Counties is as follows:  BAS09C2<st><cou>00000_<xxx>.pdf,
where <st> represents the two digit state code, <cou> represents the three digit county code, and <xxx> represents the mapsheet number.  An example of a County file name is:  BAS09C2020200000_001.pdf

• Incorporated Places:  A type of governmental unit, incorporated under state law as a city, city and borough, municipality, borough, or village that has legally prescribed limits, powers, and functions.  Incorporated place maps can be found by opening the link to the state of your interest, and then opening the link to the list of counties in that state.

The file naming convention for Incorporated Places is as follows:  BAS09P1<st>000<place>_<xxx>.pdf,
where <st> represents the two digit state code, <place> represents the five digit place code, and <xxx> represents the mapsheet number.  An example of an Incorporated Place file name is:  BAS09P10600000947_001.pdf

• Hawaiian Home Lands (HHLs):  An area created and held in trust for the benefit of native Hawaiians by the state of Hawaii, pursuant to the Hawaiian Homes Commission Act of 1920, as amended.  HHL maps can be found by opening the link to the list of HHLs on the main page.

The file naming convention for HHLs is as follows:  BAS09R4<st><yyyy><zzzz>_<xxx>.pdf,
where <st> represents the two digit state code, <yyyy> represents the four digit HHL state office code, <zzzz> represents the four digit HHL code, and <xxx> represents the mapsheet number.  An example of a HHL file name is: BAS09R49903035026_001.pdf

• Minor Civil Divisions (MCDs):  MCDs are the primary governmental or administrative divisions of counties and county equivalents in 28 states.  MCDs represent many different kinds of legal entities with a wide variety of governmental and/or administrative functions.  MCDs are variously designated as American Indian reservations, assessment districts, boroughs, charter townships, election districts, election precincts, gores, grants, locations, magisterial districts, parish governing authority districts, plantations, precincts, purchases, road districts, supervisors’ districts, towns, and townships.  MCD maps can be found by opening the link to the state of your interest, and then opening the link to the list of MCDs in that state.

The file naming convention for MCDs is as follows:  BAS09M3<st><cou><MCDcd>_<xxx>.pdf,
where <st> represents the two digit state code, <cou> represents the three digit county code, <MCDcd> represents the five digit MCD code, and <xxx> represents the mapsheet number.  An example of a MCD file name is:  BAS09M31700123412_001.pdf

The BAS entities are displayed on three different types of mapsheets:  Index, Inset, and Parent.  Index sheets show the entire entity boundary for entities that are too large to be printed on one single mapsheet.  In addition, index mapsheets also show the total number of mapsheets for that particular entity, and any inset sheets in an entity.  Index maps are assigned a mapsheet number of ‘000’.  Inset mapsheets show a larger view for areas that are too small to view in the standard parent mapsheet.  An example of an inset mapsheet number is ‘A01’.  Parent mapsheets show a portion of an entity boundary, or the entire entity boundary for those entities that are small enough to be printed on one single mapsheet.  An example of a parent mapsheet number is ‘003’.

NOTE:   Some of the maps are very large in size and downloading time for these maps will vary depending on your internet access speed.

[PDF] or denotes a file in Adobe’s Portable Document Format. To view the file, you will need the Adobe® Acrobat® Reader available free from Adobe.

Source: U.S. Census Bureau
Geography Division
Geographic Products Branch

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