Congressional Apportionment & Redistricting

Congressional apportionment — distributing the 435 fixed House seats among the 50 states — occurs every 10 years following the decennial census, under Article I, Section 2 of the Constitution and 2 U.S.C. § 2a. The Method of Equal Proportions (used since 1941) minimizes the percentage difference in district population between states. After the 2020 census: Texas gained 2 seats; Colorado, Florida, Montana, North Carolina, and Oregon each gained 1; California, Illinois, Michigan, New York, Ohio, Pennsylvania, and West Virginia each lost 1 — reflecting population shifts to Sun Belt states. Redistricting — drawing the actual district lines within each state — is where the high-stakes political battles happen. States draw their congressional and state legislative maps, typically through state legislatures (which creates obvious incentives for the party in power to gerrymander). The Supreme Court in Rucho v. Common Cause (2019) held that federal courts cannot hear claims of partisan gerrymandering — a major shift that returned gerrymandering challenges entirely to state courts and state law. Racial gerrymandering remains reviewable under the Voting Rights Act: the Supreme Court in Allen v. Milligan (2023) struck down Alabama's congressional map for diluting Black voting power, though the Court substantially narrowed that doctrine in Louisiana v. Callais, 24-109 (April 29, 2026, 6-3 Alito; Kagan dissent), holding that Section 2 did not require Louisiana to create a second majority-Black district and that race-conscious remedial maps now face a much higher bar. Approximately 18 states use some form of independent or bipartisan commission to draw maps. The 2020 redistricting cycle produced more litigation than any previous cycle, with maps in multiple states redrawn by courts.

Current Law (2026)

Parameter	Value
Constitutional basis	Article I, Section 2 (census every 10 years; apportionment among states based on population); Fourteenth Amendment, Section 2
Statutory framework	2 U.S.C. § 2a (apportionment method); 2 U.S.C. § 2c (single-member districts)
House seats	435 (fixed since 1911; permanent apportionment act of 1929)
Apportionment method	Method of equal proportions (Hill-Huntington method)
Census trigger	Decennial census → President transmits apportionment to Congress → states gain/lose seats
District drawing	Primarily state legislatures; some states use independent commissions
One person, one vote	Reynolds v. Sims (1964) — districts must be substantially equal in population
Partisan gerrymandering	Not justiciable in federal court (Rucho v. Common Cause, 2019)
Racial gerrymandering	Prohibited under Equal Protection Clause and Voting Rights Act

Legal Authority

U.S. Const. Art. I, § 2 — Representatives shall be apportioned among the several states according to their respective numbers, counting the whole number of persons in each state; an actual enumeration shall be made every ten years
2 U.S.C. § 2a — Reapportionment of Representatives (after each census, the President transmits to Congress a statement showing the number of persons in each state and the number of Representatives to which each state would be entitled under the method of equal proportions)
2 U.S.C. § 2c — Number of Congressional districts; places (each state entitled to more than one Representative shall establish single-member districts for the election of Representatives)
13 U.S.C. § 141 — Population and housing census (Secretary conducts decennial count on April 1; determines questions and methodology; must deliver apportionment population to President by December 31 of census year; detailed redistricting data to states by March 31 of following year)
13 U.S.C. § 195 — Use of sampling (statistical sampling must be used when feasible, EXCEPT for the count used to apportion Representatives — the constitutional "actual enumeration" requirement bars sampling for this purpose; Supreme Court upheld this reading in Department of Commerce v. U.S. House, 1999)
13 U.S.C. § 183 — Most recent population data for federal allocations (Secretary must provide current population estimates to the President so agencies can distribute federal funds — the link between census accuracy and over $2 trillion in annual federal spending)

How It Works

Congressional apportionment — the process of dividing 435 House seats among the 50 states based on population — and redistricting — the drawing of district boundaries within each state — are among the most consequential and politically charged processes in American democracy. They determine the fundamental unit of political representation: who represents whom.

Every ten years, the decennial census population count triggers reapportionment of the 435 House seats. The President transmits the distribution to Congress using the method of equal proportions (Hill-Huntington method) — a formula minimizing relative population differences between states, with each state guaranteed at least one seat. The stakes are real: after the 2020 census, Texas gained 2 seats while New York, California, Illinois, Michigan, Ohio, Pennsylvania, and West Virginia each lost 1, and New York's loss came by fewer than 100 people in the census count. Once a state has its seat count, it must draw district boundaries — in most states this falls to the state legislature subject to the governor's veto, giving the controlling party enormous power to gerrymander. An increasing number of states have adopted independent redistricting commissions (Arizona, California, Colorado, Michigan, Virginia, and others) to reduce partisan manipulation. All district maps must satisfy three requirements: the "one person, one vote" principle from Baker v. Carr (1962) and Reynolds v. Sims (1964) — for congressional districts, strict mathematical equality; for state legislative districts, a total deviation up to 10% — the Voting Rights Act's prohibition on racial vote dilution, and applicable state constitutional requirements for contiguity and compactness.

Gerrymandering — manipulating district boundaries for political advantage — remains one of democracy's most contested practices, using two techniques: packing (concentrating opponents' voters in a few districts to waste votes) and cracking (splitting opponents' voters across multiple districts to dilute influence). The Supreme Court held in Rucho v. Common Cause (2019) that partisan gerrymandering is a political question with no federal judicial remedy — meaning even the most extreme partisan maps are immune from federal court challenge. Racial gerrymandering, however, remains prohibited under the Equal Protection Clause and the Voting Rights Act, and district lines drawn predominantly on race face strict scrutiny — as Alabama learned in Allen v. Milligan (2023), which ordered a second majority-Black district. The Supreme Court's 6-3 ruling in Louisiana v. Callais, 24-109 (April 29, 2026), substantially narrowed that doctrine: it held that Section 2 did not require Louisiana to create a second majority-Black district and that race-conscious remedial districts now require a much stronger compelling-interest showing under the Equal Protection Clause. Justice Kagan's dissent described the decision as making Section 2 "all but a dead letter." The House has been frozen at 435 seats since 1911, meaning each member now represents approximately 770,000 people — up from about 210,000 a century ago. Proposals to expand the House and improve proportional representation arise periodically but have not advanced.

How It Affects You

If you live in a state that gained or lost House seats after the 2020 census: Your congressional districts were redrawn between 2021 and 2023 — and the lines drawn will govern your representation until at least 2031 unless courts intervene. The 2020 census shifted seats primarily from the Northeast and Midwest to the South and Southwest: Texas gained 2 seats, Florida gained 1, while New York, California, Illinois, Michigan, Ohio, and Pennsylvania each lost 1. New York lost its 27th seat by an estimated margin of fewer than 100 people in the census count — a vivid illustration of why census participation matters. In states where the legislature drew the maps, partisan control of the statehouse determined whether districts were drawn to maximize one party's advantage. In Texas, Georgia, Florida, and North Carolina, Republican legislatures drew highly favorable Republican maps. In states with independent commissions (California, Colorado, Michigan, Arizona), the process was more transparent, though not immune to litigation. If you live in a competitive district, your race is likely decided in the general election. If you live in a packed or cracked district, your party's primary winner is almost certain to win in November.

If you're concerned about gerrymandering in your state: After Rucho v. Common Cause (2019), federal courts will not hear partisan gerrymandering claims — that door is closed. Your options are state courts and state constitutional provisions. State supreme courts in North Carolina, Ohio, and New York have struck down congressional maps for partisan gerrymandering under their state constitutions — demonstrating that state law challenges remain viable even after Rucho. The most effective long-term reform is adopting an independent redistricting commission through a state ballot initiative. Arizona, California, Colorado, Michigan, and Virginia have done this. These commissions apply explicit criteria — compactness, contiguity, respect for communities of interest, and sometimes competitiveness — that constrain partisan manipulation. Contact your state's redistricting commission or legislature in 2030-2031 to submit public testimony; public participation in redistricting proceedings is explicitly required in many states and can shape outcomes.

If you're a minority voter: Redistricting is the most powerful tool for either amplifying or suppressing minority political power, and the law here is actively evolving. The Voting Rights Act Section 2 prohibits maps that dilute minority voting strength — you cannot "crack" a geographically compact minority community across multiple districts to prevent it from electing a representative of its choice. Allen v. Milligan (2023) reaffirmed that Alabama violated Section 2 by drawing a congressional map with only one majority-Black district when population would support two — the Court ordered Alabama to draw a second opportunity district. That case, combined with Thornburg v. Gingles (1986), is the analytical framework for VRA redistricting claims. At the same time, courts distinguish between impermissible racial gerrymandering (drawing districts predominantly based on race without sufficient justification) and required minority opportunity districts — the line between them is actively litigated. If your community believes a map dilutes your voting strength, contact the NAACP Legal Defense Fund, MALDEF, or similar organizations that litigate VRA redistricting cases.

If you work in policy, advocacy, or data analysis around elections: The 2030 redistricting cycle will be shaped by three open questions. First, the Supreme Court's Loper Bright doctrine (2024, overruling Chevron deference) has uncertain implications for VRA enforcement, since agencies no longer get deference for their interpretations of ambiguous statutory language. Second, the debate over whether to count only citizens (rather than total population) for apportionment is live — HR 7167 would add a citizenship checkbox to the 2030 census and exclude noncitizens from apportionment, which would shift seats from high-immigration states (California, New York, Texas) to lower-immigration states. Third, the prison gerrymandering issue — counting incarcerated people at the prison location rather than their home community — inflates the representation of rural districts with large prisons at the expense of urban communities from which most prisoners come. Several states (NY, CA, IL) have enacted prison reallocation statutes that count prisoners at their last home address for state redistricting, but federal law (the decennial census) continues to count them at the prison.

State Variations

District-drawing authority varies: state legislatures (most states), independent commissions (AZ, CA, CO, MI, VA, others), advisory commissions, or hybrid approaches
State constitutions may impose additional redistricting criteria (compactness, contiguity, preservation of communities of interest, competitiveness)
State courts play an increasingly important role in reviewing redistricting plans, particularly for partisan gerrymandering (which federal courts won't address)
Several states use independent commissions for state legislative districts but not congressional districts (or vice versa)
States with only one House seat (Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont, Wyoming) don't draw congressional districts

Implementing Regulations

Census procedures and apportionment mechanics are governed primarily by Title 13, United States Code (Census Bureau authority) and 2 U.S.C. Chapter 1 rather than detailed implementing regulations in the Code of Federal Regulations. The Census Bureau's operational rules (13 CFR) address statistical methodology, confidentiality, and data collection procedures but do not prescribe substantive apportionment or redistricting rules. Redistricting standards are established through constitutional requirements (equal population), the Voting Rights Act, and state law rather than federal administrative regulations.

Pending Legislation

HR 5921 — Require nationwide public websites and hearings for redistricting transparency. Status: Introduced.
HR 7219 — Set national rules for maps, exclude unauthorized immigrants from apportionment. Status: Introduced.
HR 7375 — Count incarcerated people at pre-incarceration residence for redistricting. Status: Introduced.
HR 7167 — Add citizenship checkbox to 2030 census, exclude noncitizens from apportionment. Status: Introduced.
HR 5879 — Bar mid-decade congressional map changes. Status: Introduced.
HR 5449 (Rep. Lofgren, D-CA) — Federal framework requiring independent redistricting commissions. Status: Introduced.
S 2885 (Sen. Padilla, D-CA) — Require states to use independent redistricting commissions. Status: Introduced.

Recent Developments

The 2020 census redistricting cycle produced intense litigation across the country, with challenges to maps in multiple states on partisan gerrymandering (state courts) and racial gerrymandering (federal courts) grounds
Allen v. Milligan (2023) reaffirmed the Voting Rights Act's application to redistricting, requiring Alabama to draw a second majority-Black congressional district
Independent redistricting commissions gained ground in the 2020 cycle, with new commissions operating in Virginia and Colorado
State supreme courts struck down congressional maps for partisan gerrymandering in several states (North Carolina, Ohio, New York)
The debate over expanding the House from 435 seats continues but has not resulted in legislation
In early 2026, California Republicans urged the Supreme Court to strike the state's congressional map as racially discriminatory, following the Court's December 2025 decision allowing Texas to use a new congressional map that gave Republicans additional seats despite a lower court challenge.
Louisiana v. Callais, 24-109 (April 29, 2026): A 6-3 Supreme Court (Alito majority joined by Roberts, Thomas, Gorsuch, Kavanaugh, and Barrett; Kagan dissenting joined by Sotomayor and Jackson) held that Section 2 of the VRA did not require Louisiana to create a second majority-Black congressional district, and that the State therefore lacked a compelling governmental interest under the Equal Protection Clause to use race in drawing one. The decision substantially narrows Allen v. Milligan — court-ordered creation of new majority-minority districts as a Section 2 remedy is now substantially harder, and prior Section 2 victories ordering remedial maps are vulnerable to renewed challenge. Kagan dissent: § 2 "all but a dead letter." In May 2026, Alabama AG Steve Marshall filed emergency motions asking the Supreme Court to lift the Allen v. Milligan injunction in light of Callais before the May 19, 2026 primary; a three-judge panel below denied a parallel state request, holding only the Supreme Court can address the substance.