Apportionment  -  The number of representatives that a state is entitled to in the U. S. House of Representatives based on the decennial census.  See reapportionment and redistricting.

Block  (Census Block)  -  A geographic area bounded on all sides by visible or nonvisble features shown on census maps.  A block is the smallest geographic entity for which the Census Bureau collects and tabulates decennial census information.

Block Boundary  -  A census map feature, visible (street, road, stream, shoreline, etc.) or nonvisible (county line, city limit, property line, etc.), that delimits a census block.  Two or more features usually delimit a block, but a single feature may delimit a block in the case of an island or a circular street.  A boundary generally must include at least one feature that can have an address assigned to it.  The boundary of a state or county is always a block boundary.

Boundary and Annexation Survey (BAS)  -  An annual survey of all incorporated places and all counties conducted by the U.S. Census Bureau to determine the correct legal limits and related information as of January 1 of the survey year. 

Census  -  A complete enumeration of a population or the business and commercial establishments, farms, or governments in an area.

Census Designated Place (CDP)  -  A statistical entity comprising a dense concentration of population that is not within an incorporated place but is locally identified by a name.  CDPs are delineated cooperatively with state and local and tribal government officials based on U.S. Census Bureau guidelines.

Census Geography  -  A collective term referring to the geographic entities used by the U.S. Census Bureau for data collection and tabulation.

Feature  -  Any part of the landscape, whether natural (such as a stream or ridge) or artificial (such as a road or power line).  In geographic context, features are any part of the landscape portrayed on a map, including nonvisible boundaries of legal entities, such as city limits and county lines.

Public Law 94-171 (P.L. 94-171)  -  The  federal public law requiring the U.S. Census Bureau to provide selected decennial census data tabulations to the states by April 1 of the year following the census.  These tabulations are used by the states to redefine the areas included in each congressional district and the other districts used for state and local elections, a process called redistricting.

Reapportionment  -  The reallocation of seats in the U. S. House of Representatives among several states on the basis of the most recent decennial census as required by Article 1, Section 2 of the U.S. Constitution.

Redistricting  -  The process of revising the geographic boundaries of an area from which people elect representatives to the U. S. Congress, a state legislature, a county or city council, a school board, or other political subdivision.

Standard deviation  -  A measure of the dispersion of values in a frequency distribution from the average.

Topologically Integrated Geographic Encoding and Referencing (TIGER)  -  A computer database that contains a digital representation of all census-required map features (streets, roads, rivers, railroads, lakes, etc.), the related attributes for each, and the geographic identification codes for all entities used by the Census Bureau to tabulate data for the United States, Puerto Rico, and Island Areas.  The TIGER® database provides a resource for the production of maps, entity headers for tabulations, and other processes.

TIGER®/Line File  -  The computer-readable extract of the TIGER database that the Census Bureau makes available to the public.  It contains data representing the roads, railroads, bodies of water, boundaries of legal and statistical entities, and other visible and nonvisible features, along with their attributes (names, address ranges, geographic codes, census feature class codes, and the like).

Voter District  (VTD)  - Any variety of types of areas, such as election precincts, precincts, wards, and legislative districts established by state and local governments for purposes of elections.  For the purpose of redistricting in Wyoming, VTD refers  to an area closely related to election precincts established by the county clerks.