Redistricting is the process of drawing the boundaries for election districts so that communities can elect representatives. In the United States, this usually happens after each census, which counts the population every 10 years. The goal is to keep districts nearly equal in population so each person's vote has roughly equal weight.
Redistricting matters because district lines can influence which candidates win and which communities have political power.
Census data shows where people live, how populations have shifted, and how many seats each state receives in the U.S. House of Representatives. State legislatures, independent commissions, or courts may draw the maps depending on state law. Good maps follow rules such as equal population, protection of voting rights, compactness, and respect for communities of interest.
Political actors may also try to shape maps for advantage, which is why transparency and public input are important.
Understanding Civics: Redistricting and the Census
Census results do more than produce a national population total. They are released in detailed geographic units, including census blocks. A block can be as small as one side of a street or a city block.
Mapmakers combine thousands of these units to build districts with the required population. They must use the official count, even though people may have moved by the time a new map takes effect.
Some groups are harder to count, including renters, young children, people without stable housing, and people who distrust government forms. An undercount can reduce a community's representation for a full decade, so completing the census has a direct civic effect.
The mapmaking process has several stages. First, officials learn how many U.S. House seats each state will have after apportionment.
A state that gains a seat must create a new district. A state that loses one must combine areas that once had separate representatives. Then mapmakers set a target population for each district.
Congressional districts usually need to be extremely close to that target. State legislative districts have similar rules, though small differences may sometimes be allowed for practical reasons. A map must usually keep every district connected.
This is called contiguity. Islands can create exceptions when geography makes a connection impossible.
Equal population does not settle every decision. A town may be split between districts to balance the numbers, but splitting it can weaken its shared voice on local issues such as water, roads, schools, or farming. Keeping neighborhoods together may conflict with making a district compact.
Compactness means a district is not stretched across distant places without a clear reason. No single shape proves that a map is fair.
Real communities can have unusual shapes because of coastlines, mountains, city growth, or transportation routes. Students should pay attention to the reasons given for each boundary, not only whether a map looks tidy.
Gerrymandering often works through packing or cracking. Packing places many voters with similar views into one district, where they elect one representative by a very large margin but have less influence nearby. Cracking spreads those voters across several districts so they are too few to choose a candidate in any of them.
Federal voting rights law can require maps to give racial or language minority communities a fair opportunity to elect preferred candidates when legal conditions are met. Courts may review maps that appear to violate these protections or other constitutional rules.
Public hearings, draft maps, and written comments give residents a way to point out community ties that data alone cannot show. When studying a map, compare it with population data, city boundaries, past election results, and the location of communities that may be divided.
Key Facts
- The U.S. census occurs every 10 years and is required by the Constitution.
- Apportionment assigns U.S. House seats to states based on census population counts.
- Redistricting redraws district boundaries within a state after population changes.
- One-person-one-vote means districts must have nearly equal populations.
- Ideal district population = state population ÷ number of districts.
- Gerrymandering is drawing district lines to give a political party or group an unfair advantage.
Vocabulary
- Census
- A census is an official count of the population, usually including information about where people live.
- Redistricting
- Redistricting is the process of redrawing election district boundaries after population changes.
- Apportionment
- Apportionment is the process of dividing seats in a legislative body among states or regions based on population.
- District
- A district is a geographic area whose voters elect one or more representatives.
- Gerrymandering
- Gerrymandering is the manipulation of district boundaries to benefit a party, candidate, or group.
Common Mistakes to Avoid
- Thinking the census only counts voters. The census counts all residents, including children and noncitizens, because representation is based on total population.
- Assuming districts never change. Districts are redrawn after census data shows population growth, decline, or movement within a state.
- Confusing apportionment with redistricting. Apportionment decides how many seats a state gets, while redistricting decides where the district lines go inside the state.
- Believing equal land area means fair districts. Districts are based mainly on population, so a dense city district may cover much less land than a rural district.
Practice Questions
- 1 A state has a population of 5,000,000 and 10 congressional districts. What is the ideal population for each district?
- 2 A state has 4 districts with populations of 755,000, 748,000, 762,000, and 735,000. What is the total state population, and what is the ideal district population?
- 3 A map places most voters from one political party into a few districts while spreading the other party's voters across many districts. Explain why this may be considered gerrymandering and how it can affect representation.