Redistricting Words and Phrases
- Alternative Population Base:
- A population count other than the official census data that is used for redistricting.
- Apportionment:
- The process of assigning the number of members of Congress that each state may elect following each census.
- At-Large:
- When one or several candidates run for an office, and they are elected by the whole area of a local political subdivision, they are being elected at-large
- Black Voting Age Percentage (BVAP):
- The percentage of population of blacks, 18 years or older
- Census:
- Enumeration or count of the population as mandated by the United States Constitution.
- Census Block:
- The smallest unit of geography used by the Census Bureau for counting people. Blocks are almost always bounded by visible features such as roads and rivers.
- Census Tract:
- Geographic areas made up of block groups recommended by the states and used by the Census Bureau for the collection and presentation of decennial census data.
- Community of Interest:
- Communities defined by actual shared interests, either political, social or economic.
- Compactness:
- Having the minimum distance between all the parts of a constituency (a circle or hexagon is the most compact district). There are various methods of measuring compactness.
- Contiguity:
- All parts of a district being connected at some point with the rest of the district and not divided into two or more discrete pieces. Adjacency.
- Deviation:
- The degree by which a single district's population varies from the "ideal" may be stated in terms of "absolute deviation" or "relative deviation." "Absolute deviation" is equal to the difference between its population and the "ideal" population, expressed as a plus (+) or minus (-) number that the district's population exceeds or falls short of. "Relative deviation" is the more commonly used measure and is attained by dividing the district's absolute deviation by the "ideal" population.
- Differential Undercount:
- The difference in the undercount between ethnic groups. The undercount for ethnic groups has traditionally been higher than for whites.
- Digital Map Layer:
- A set of polygons representing geographic units. For redistricting, the primary map layers used include the following:
- Minor Civil Divisions (MCD):
- Includes cities, towns, and villages.
- Voting Tabulation Districts (VTD):
- Wards inside MCDs, election districts in rural areas.
- Census Blocks (CNS):
- The smallest unit of census geography, normally bounded on all sides by visible features such as city or county limits, property lines, and imaginary extensions of roads.
- Elections Data:
- Actual votes for each candidate in primaries and general elections; some Minor Civil Divisions, however, do not report data for every ward for every election.
- Fracturing/Fragmentation:
- Splitting an area where a minority group lives so that it cannot form an effective majority in a district, for the purpose of minimizing the group's voting strength.
- Gerrymander:
- The drawing of districts in a way that gives one group or party advantage over another.
- Geographic Information System (GIS):
- A computer based method for the automation, storage, manipulation, integration, analysis, display and dissemination of spatial data and related attribute data in the form of maps.
- Homogenous District:
- A voting district with at least 90 percent minority or white population.
- Ideal District Population:
- A population measure equal to the total state population divided by the total number of districts.
- Majority-Minority Districts:
- Term used by the courts for seats where an ethnic minority constitutes a majority of the population.
- Metes & Bounds:
- A detailed description of district boundaries using specific geographic features.
- Method of Equal Proportions:
- Mathematical formula provided by federal statute to reapportion congressional seats after each decennial census.
- Minor Civil Division (MCD):
- A supervisor’s district, police jury district or township. Typically, subdivisions of a county.
- Multi-Member District:
- A district that elects two or more members to a legislative body.
- Natural Boundaries (Visible Boundaries):
- District boundaries that are natural geographic features.
- One Person, One Vote:
- Constitutional standard established by the Supreme Court that all legislative districts should be approximately equal in population.
- Overall Range or Overall Deviation:
- For a redistricting plan, the difference in population between the smallest and largest district, normally expressed as a percentage.
- Packing:
- A term used when one group is consolidated into a small number of districts in a districting plan. Drawing a minority-controlled district with an excessively high percentage of a minority population, "wasting" the additional people who could increase the minority population of another district.
- Phase I and Phase II:
- Programs run by the Census Bureau to collect boundary information from state and local governments. Phase I allows states to suggest boundaries for census blocks. Phase II lets state's group blocks into precincts so the official census data will contain precinct population totals.
- PL 94-171:
- Law passed in 1975 by Congress that requires the Census Bureau to furnish state governments data by April 1 of the year after the census for use in redistricting. The law requires that the bureau allow states to define the boundaries of the areas in which population data is collected.
- Plurality:
- A winning total in an election involving more than two candidates, where the winner received less than a majority of the votes cast.
- Population Estimate:
- An approximation of the population of a geographic unit at a point in the past or present for which an actual population count is not available.
- Reapportionment:
- The allocation of seats in a legislative body (such as Congress) among established districts (such as states), where the district boundaries do not change but the number of members per district does.
- Redistricting:
- The drawing of new political district boundaries.
- Retrogression:
- Drawing a redistricting plan that reduces the chances for minority groups to elect representatives of their choice.
- Sampling:
- A statistical technique used to estimate the whole population based on a sample. Proposed as a remedy for the undercount.
- Single-Member District:
- District that elects only one representative.
- Standard Deviation:
- A statistical formula measuring variance from a norm.
- Tabulation:
- The totaling and reporting of the census data.
- Topologically Integrated Geographic Encoding and Referencing (TIGER):
- The TIGER/Line files are a digital database of geographic features, such as roads, railroads, rivers, lakes, political boundaries, census statistical boundaries, etc. covering the entire United States. The data base contains information about these features such as their location in latitude and longitude, the name, the type of feature, address ranges for most streets, the geographic relationship to other features, and other related information. TIGER was developed at the Census Bureau to support the mapping and related geographic activities required by the decennial census and sample survey programs.
- Undercount:
- The estimated number of people who are not counted by the census.
- Voting Age Population (VAP):
- The number of people over the age of 18.
- Voting Rights Act:
- Federal law prohibiting discrimination in voting practices on the basis of race or language group.
- Voting Tabulation District (VTD):
- The census geographic equivalent of a county election precinct, created for the purpose of relating elections data to census data.