Glossary of Terms

Apportionment – The number of representatives to which a state is entitled 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 nonvisible features shown on census maps. A block is the smallest geographic entity for which the U.S. Census Bureau collects and tabulates decennial census information.
 
Block Boundary – A census map feature, visible (such as street, road, stream, shoreline) or nonvisible (such as county line, city limit, property line), 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 Jan. 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 that 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.

Voter District – 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.