Texas Redistricting

Redistricting Glossary

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A method used to report election data for redistricting purposes. Election data is reported at the county precinct level. Population data from the decennial census is reported at the census geographies. Since election precincts are not required to be created using census geography, there is not a natural connection between election data and population data. To remedy this situation, the council uses a mathematical algorithm to allocate election data from the county precinct level down to the census block.

American Community Survey (ACS)
An ongoing census survey conducted by the Census Bureau by contacting a sample of more than 3.5 million households each year. The ACS collects detailed demographic and socioeconomic population and housing characteristics, similar to the information collected on the former long-form census questionnaire. The data is collected continuously rather than once a decade, so the ACS may provide more current data than the decennial census. Single‐year estimates are available annually for geographic areas with a population of 65,000 or more, and five‐year estimates are available for certain geographic areas, including legislative districts.

As commonly used in Texas, those persons who identified their race on the census form as White only and who do not identify themselves as of Hispanic, Latino, or Spanish origin.

Those persons who identify their race on the census form as Chinese, Filipino, Asian Indian, Vietnamese, Korean, Japanese, or other Asian.

Assignment unit
Any unit of geography that may be used as a building block to draw a redistricting plan. Assignment units available in RedAppl are counties, census tracts, census block groups, census blocks, and VTDs (voting tabulation districts).

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Those persons who identified their race on the census form as Black or African American.

Black + Hispanic
A combined population category that includes all persons who identify their race on the census form as Black or African American and all persons who identify themselves on the census form as of Hispanic, Latino, or Spanish origin, without counting anyone twice. The category is frequently examined for redistricting purposes in areas in which Black and Hispanic voters may form political coalitions or vote together as a bloc.

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Census block
The smallest unit of census geography for which population data are counted and reported. Census blocks are delineated by the Census Bureau and are generally bounded by physical features such as roads, creeks, or shorelines, but also may be bounded by nonvisible features such as city, county, school district, or voting precinct boundaries.

Census block group
A subdivision of a census tract composed of a group of contiguous census blocks with the same first digit of their four‐digit census block number. Block groups generally contain between 600 and 3,000 people.

Census day
April 1, 2020, is census day for the 2020 decennial census, the date for which census data is collected. Federal law designates April 1 of each decennial census year as census day.

Census Designated Place (CDP)
Statistical geographic entities representing settled, unincorporated communities that are locally identified by a name.

Census tract
A unit of census geography delineated by local committees in accordance with Census Bureau guidelines for the purpose of collecting and presenting decennial census data. Census tracts are made up of block groups. Their boundaries generally follow visible features, though in some circumstances their boundaries may follow governmental unit boundaries such as city limits or other nonvisible features. In general, census tracts contain between 2,500 and 8,000 people, with an optimum population size of 4,000.

Citizen Voting Age Population (CVAP)
The number of United States citizens in a geographic unit who are at least 18 years of age.

Community of interest
A term sometimes used to describe a grouping of people in a geographical area, such as a specific region or neighborhood, who have common political, social, or economic interests.

A basic redistricting principle that generally refers to the geographic shape of a district and how that district's territory is dispersed within its boundaries. Courts often refer to compactness as a traditional redistricting principle and may examine compactness when considering the extent to which a district is gerrymandered. In redistricting, compactness is frequently analyzed using methods that focus on the dispersion of the area of the district, the relation of the perimeter of the district to its area, or the dispersion of the population of the district.

Legal standards governing redistricting for various governmental bodies often require all of the territory in each district to be contiguous. For redistricting purposes, a district is usually considered to be contiguous if all parts of the district touch one another at more than a point, so that the entire district is within a continuous boundary.

County election precincts
Also called county voting precincts. Geographic units established by county commissioners courts for the purpose of election administration. The votes cast by the voters residing in a precinct are usually counted separately from other precincts.

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The amount or percentage by which a district's population differs from the ideal district population for the particular district type.

Differential Privacy
The scientific term for a method that adds "statistical noise" to the tables that the Census Bureau publishes in a way that protects each respondent's identity. Differential privacy uses statistical noise to slightly alter data so that the link between the data and a specific person or business can't be certain. With differential privacy, the Census Bureau precisely controls the amount of statistical noise added using sophisticated mathematical formulas that allow them to assure that enough noise is added to protect privacy but not so much as to damage the statistical validity of their publications. The formulas allow the bureau to balance between two opposing extremes: total accuracy and total privacy. In practice, this means that areas that have a large number of people will have highly accurate statistics, but areas or subpopulations that have just a few people will have proportionately more noise and therefore less accuracy. In this way, the statistical noise prevents someone from learning anything meaningful about any particular individual.

The web application maintained by the Texas Legislature for viewing interactive maps of current Texas legislative, congressional, and State Board of Education (SBOE) districts over the Internet.

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Equal Protection Clause
See "Fourteenth Amendment to the U.S. Constitution."

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Fifteenth Amendment to the U.S. Constitution
The provision of the U.S. Constitution that prohibits the right to vote from being denied or abridged on account of "race, color, or previous condition of servitude."

Fourteenth Amendment to the U.S. Constitution
The provision of the U.S. Constitution that includes the Equal Protection Clause, which prohibits the states from denying persons equal protection of the law. The Equal Protection Clause is the primary basis of the one‐person, one‐vote principle.

The division of members of a geographically concentrated group, such as a racial or political group, among different districts for the purpose of minimizing the group's voting strength.

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Geographic Information System (GIS)
A graphics‐based computer system that relates geographic features (such as census tracts, cities, VTDs, or counties) to data about those features (such as population, race, or voting behavior).

To draw a district or set of districts with unusual boundaries usually with the intent to favor one group or party over another.

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Those persons who identify themselves on the census form as of Hispanic, Latino, or Spanish origin. Hispanic persons can be of any race.

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Ideal district population
A measure calculated by dividing the total population of the state or other jurisdiction being redistricted by the number of districts in the legislative body or board being redistricted. For example, in 2010, the ideal district population for Texas Senate districts was 811,147, which is the 2010 state population (25,145,561) divided by the number of districts in the Texas Senate (31).

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Legislative Redistricting Board (LRB)
The state entity responsible for adopting redistricting plans for the Texas Senate and the Texas House of Representatives if the Texas Legislature fails to enact those plans during the regular session following the publication of the decennial census. The Legislative Redistricting Board consists of the lieutenant governor, speaker of the house, attorney general, comptroller, and commissioner of the General Land Office. See Section 28, Article III, Texas Constitution.

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Method of equal proportions
The mathematical formula prescribed by federal statute that is used to reapportion congressional seats among the states after each decennial census.

Minority vote dilution
A general term used to describe practices that limit or cancel a racial or ethnic minority group's voting strength or electoral effectiveness. In redistricting, minority vote dilution may occur when districts are created that fragment (see "Fragmentation") or pack (see "Packing") members of a racial or ethnic minority group in a way that reduces the group's opportunity to influence elections.

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One‐person, one‐vote
The constitutional requirement that one person's vote must count the same or substantially the same as another person's vote, which is achieved by allocating the same or substantially the same number of people to each district of a particular type, such as a congressional district. For legislative districts, the one‐person, one‐vote standard derives from the Equal Protection Clause of the Fourteenth Amendment to the U.S. Constitution. For congressional districts, the one‐person, one‐vote standard derives from Section 2, Article I, of the U.S. Constitution and from Section 2 of the Fourteenth Amendment to the U.S. Constitution.

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P.L. (Public Law) 94‐171
The federal statute that requires the Census Bureau to provide, by April 1 of each year following a decennial census, the census data necessary for redistricting.

P.L. (Public Law) 105‐119
The 1997 federal statute that requires the Census Bureau to make publicly available the census data resulting from the actual responses to the census forms and follow‐up efforts, without any statistical adjustments to correct for overcounts and undercounts.

P.L. Data
A term used to describe the population data from the federal decennial census that is delivered to the states under P.L. 94‐171 and P.L. 105‐119 in the year after the year in which the census is conducted.

The inclusion in a district of an artificially high concentration of a particular group of voters, such as a racial or political group, which tends to result in the election of the group's candidate of choice in that district while diluting the group's voting strength in neighboring districts due to the "wasting" of votes in the packed district.

Population estimates
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.

Population projections
An approximation of the population of a geographic unit at a point in the future based on specific assumptions regarding future demographic trends in the geographic unit.

Approval by the U.S. Department of Justice or a special three‐judge panel of the U.S. District Court for the District of Columbia under Section 5 of the Voting Rights Act of 1965 of a redistricting plan or other proposed change in an election practice or procedure of a "covered jurisdiction," such as Texas, before the change may be applied. As a result of the 2013 U.S. Supreme Court ruling in Shelby County v. Holder, preclearance under Section 5 is no longer required in covered jurisdictions, including Texas. However, a jurisdiction that is held to have engaged in intentional discrimination against minority voters may be required to seek preclearance of a new voting change by a federal court under Section 3 of the Voting Rights Act of 1965, frequently referred to as the "bail‐in" provision.

Public plan
A redistricting proposal that has been made public through the legislative process or otherwise publicly released by its author.

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Racially polarized voting
The term used to describe circumstances in which the voting preferences of a racial or ethnic group consistently vary from those of other racial or ethnic groups, particularly when the different voting preferences are based on the race of the candidate. Also referred to as "racial bloc voting."

Reallocation of a fixed number of seats in a governmental body among established political units. Following each decennial census, the seats in the U.S. House of Representatives are reapportioned among the states. The result is that each state is assigned its number of congressional seats for the next decade. Reapportionment does not redefine district boundaries. The term is sometimes used imprecisely to mean "redistricting."

The Texas Legislature's geographic information system (GIS) application developed by the Texas Legislative Council used for redistricting.

The process of redefining the geographic boundaries of individual election units, such as legislative or congressional districts or county election precincts.

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Spanish Surname Voter Registration (SSVR)
A precinct‐level summation of registered voters with Spanish surnames, as identified by the Texas Secretary of State from a Hispanic surname list prepared by the Census Bureau, last updated in 2002. SSVR is often used to help ascertain the number of Hispanic voters who reside in a district.

Statistical sampling
The statistical method by which characteristics of a small group are measured and applied to the population as a whole.

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Topologically Integrated Geographic Encoding and Referencing System (TIGER)
The cartographic map database maintained by the Census Bureau for purposes of reporting census data by block, block group, tract, or other geographic unit. Texas and most other jurisdictions use the TIGER maps as the geographic database for redistricting.

Total range of deviation
The range over which the populations of all districts in a redistricting plan deviate from the ideal district population, computed by examining the deviations of the most populous and least populous districts.

Traditional districting principles
A term often used to refer to neutral or benign criteria, such as compactness, contiguity, and the preservation of political subdivisions and communities of interest, that have historically been considered in drawing legislative or other districts.

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The error in census data that results from the failure to count some persons or housing units in the decennial census. Historically, certain groups, such as members of racial, ethnic, or socioeconomic groups, have been disproportionately undercounted by the federal census.

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Voter registration (VR)
The number of persons registered to vote in a county or other geographic unit. On redistricting reports used by the Texas Legislature, total voter registration is the total number of persons listed on a county's voter registration roll for the geographic unit. Non‐suspense voter registration is total voter registration minus the number of registered voters who failed to respond to a confirmation of residence notice sent by the county voter registrar.

Voting age population (VAP)
The number of persons in a geographic unit who are at least 18 years of age. Because some population groups, such as those composed of racial or ethnic minority groups, tend to be younger on average than the population as a whole, the voting age populations are frequently compared in evaluating the potential voting strength of those groups.

Voting Rights Act of 1965
The landmark federal law, originally enacted in 1965 and amended several times since its enactment, that prohibits discrimination in voting practices on the basis of race or membership in a language minority group, codified as 52 U.S.C. Section 10101 et seq. Section 2 of the act prohibits the adoption of voting standards or practices that abridge the right to vote on the basis of race or language group and is frequently used to challenge a redistricting plan that is alleged to discriminate against a racial or language minority group.

Voting Tabulation District (VTD)
The census geographic equivalent of a county election precinct, created for the purpose of relating election data to census data. VTDs can differ from actual election precincts because election precincts do not always follow census geography. During the approximation process that creates VTDs, county election precinct boundaries that do not follow census geography are assigned to the nearest census block boundary.

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Who Represents Me?
The Texas Legislature's address matching system that identifies the member of the United States Congress, the Texas Senate, the Texas House of Representatives, and the State Board of Education who represents a user‐entered location. https://wrm.capitol.texas.gov/home/

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