Congressional districts are geographic boundaries within a state that define the area a single member of the US House of Representatives is elected to represent. The United States has 435 House seats—and thus 435 congressional districts—split among the 50 states depending on population. Within each state, the Constitution calls for congressional districts to be roughly equal in terms of the number of people represented within them. However, the Constitution does not specify how that equality should be achieved.
How are congressional districts drawn?
The number of House seats to which a state is entitled is determined through a process called apportionment. Every 10 years, following the national Census, House seats are redivided among the states, and congressional districts are redrawn to account for population changes. Redistricting processes vary from state to state. In many cases state legislatures oversee redistricting. In some, independent commissions handle the redistricting process to prevent gerrymandering.
What is gerrymandering?
Gerrymandering is the intentional drawing of districts to favor a particular political party, candidate, or group. The term was first used in 1812, when state senate districts in Massachusetts were redrawn to benefit the Democratic-Republican Party under the leadership of Governor Elbridge Gerry. Some people thought one of the oddly shaped districts looked like a salamander, so a newspaper illustration dubbed it "The Gerry-mander," a term that came to describe any district drawn for political advantage.
Types of gerrymandering
Cracking takes a group of voters and spreads them out across many districts to dilute their influence enough that they are not able to elect any representatives.
Packing crams a group of voters into as few districts as possible. While members of the group may be able to elect one representative, they are prevented from broader influence.
How can gerrymandering be avoided?
Citizens have pursued several strategies to prevent gerrymandering:
Independent commissions: In order to limit the power of self-interested politicians in the mapmaking process, independent commissions control redistricting. Nearly half of all US states have such commissions made up of bipartisan or nonpartisan participants.
Legislation: Over the past two decades, a number of bills have been introduced in Congress to prohibit partisan gerrymandering, but none have passed.
Legal action: Lawsuits alleging racial bias have successfully challenged gerrymandered districts in some cases.
Can redistricting happen even if there hasn't been a new Census?
Yes. While the Constitution requires that all federal and state election district boundaries be redrawn after new census data is collected every 10 years, it does not prevent redistricting at other times.
Some states prohibit mid-decade congressional redistricting, however most state constitutions do not address the question.
