How Does Redistricting Work?

Redistricting is the process of redrawing the boundaries of electoral districts to reflect population changes identified in the U.S. census. After each decennial census, states redraw district lines so that each district contains roughly equal populations. District maps must comply with federal law, including the Equal Protection Clause and the Voting Rights Act of 1965. In many states, the legislature draws the maps, while others use independent or bipartisan commissions.

What Is the Purpose of Redistricting?

The primary purpose of redistricting is to ensure equal representation in government as populations shift over time. This principle stems from Supreme Court decisions establishing "one person, one vote," ensuring votes carry roughly equal weight across districts. Redistricting also ensures compliance with the Voting Rights Act, which prohibits district lines from diluting the voting strength of racial or language minority groups.

How Often Does Redistricting Happen?

Redistricting occurs once every ten years, following the completion of the national census. Article I, Section 2 of the United States Constitution requires a census every decade. After census data is finalized and congressional seats are reapportioned among the states, each state redraws its district boundaries. Courts may also require states to revise district maps mid-decade if they are found to violate constitutional standards or federal law.

Who Is Responsible for Redistricting?

Responsibility for redistricting primarily rests with state governments. In most states, the state legislature drafts and approves new district maps, subject to the governor's approval. Some states use independent or bipartisan redistricting commissions to reduce partisan influence. If a state cannot agree on a map or if a map is challenged in court, state or federal courts may step in to establish or revise district boundaries.

Congressional Redistricting

Overview

Congressional redistricting is the process by which states redraw electoral district boundaries that determine representation in the US House of Representatives. The Constitution, federal law, and court rulings require districts to have roughly equal populations, avoid discrimination against racial or language minorities, and, in most states, be geographically contiguous. For most of American history, redistricting has followed a predictable cycle, occurring every 10 years after the census.

Gerrymandering is the deliberate manipulation of district boundaries to advantage one political party. Common tactics by both major American political parties include packing opposition voters into a small number of districts and cracking them across many districts to dilute their influence. Enabled by detailed voter data and advanced mapping software, modern gerrymandering can extend down to individual streets or blocks. Most scholars agree that it weakens democratic accountability by reducing competition and insulating incumbents.

The practice dates back to the beginning of the American republic but was constrained during the Civil Rights era, particularly after the Voting Rights Act of 1965. Court decisions and technological advances have since reduced many of those constraints.

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: Redistricting is the process of redrawing the boundaries of electoral districts to reflect population changes identified in the U.S. census. After each decennial census, states redraw district lines so that each district contains roughly equal populations. District maps must comply with federal law, including the Equal Protection Clause and the Voting Rights Act of 1965. In many states, the legislature draws the maps, while others use independent or bipartisan commissions.
: The primary purpose of redistricting is to ensure equal representation in government as populations shift over time. This principle stems from Supreme Court decisions establishing "one person, one vote," ensuring votes carry roughly equal weight across districts. Redistricting also ensures compliance with the Voting Rights Act, which prohibits district lines from diluting the voting strength of racial or language minority groups.
: Redistricting occurs once every ten years, following the completion of the national census. Article I, Section 2 of the United States Constitution requires a census every decade. After census data is finalized and congressional seats are reapportioned among the states, each state redraws its district boundaries. Courts may also require states to revise district maps mid-decade if they are found to violate constitutional standards or federal law.
: Responsibility for redistricting primarily rests with state governments. In most states, the state legislature drafts and approves new district maps, subject to the governor's approval. Some states use independent or bipartisan redistricting commissions to reduce partisan influence. If a state cannot agree on a map or if a map is challenged in court, state or federal courts may step in to establish or revise district boundaries.

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