Congressional Apportionment · Data Analysis
Who Counts?
VAP, CVAP and the House
The U.S. House is apportioned using total resident population — citizens and non-citizens alike. This analysis models how seat allocations would shift under citizen-only population and citizen voting-age population (CVAP).
Total population
—
Updated 2024 ACS
Citizen population
—
Updated 2024 ACS
CVAP (citizens 18+)
—
Fully updated
House seats
435
Fixed by Apportionment Act, 1929
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Seat change:
Scenarios & methodology
01
Current law — total population
Total resident population of all ages and citizenship statuses. Required by the 14th Amendment as interpreted by statute. Applied at each decennial census; current apportionment runs 2020–2030.
02
Citizen population (all ages)
Total citizens regardless of age. Estimated by applying state-level non-citizen rates from ACS B05001 to total population. This basis has never been enacted and remains legally contested — the 14th Amendment's instruction to count the "whole number of persons" has historically been interpreted to include non-citizens, and no Supreme Court ruling has definitively resolved whether citizen-only apportionment would be constitutional.
03
CVAP — citizen voting-age pop.
Citizens aged 18 and older — the eligible electorate. The most restrictive apportionment basis. Computed as: total pop × (VAP% − non-citizen% × 0.90). The 0.90 multiplier is a modeling adjustment that recognizes citizenship alone does not guarantee voting eligibility — a portion of the citizen voting-age population is ineligible due to factors such as felony disenfranchisement, mental incapacity determinations, or other state-level legal disqualifications. Applying a 10% reduction to the non-citizen share produces a more conservative and realistic estimate of the truly eligible citizen electorate, rather than treating all citizens 18 and over as uniformly eligible.
Method of Equal Proportions — priority value
Priority = Population ÷ √(n × (n + 1))
Each state is guaranteed one seat (50 total). The remaining 385 seats are awarded one at a time to whichever state has the highest priority value, where n is that state's current seat count. In use since 1941.
Data sources: Total population & VAP%: 2024 ACS 5-year estimates, table B01001 (U.S. Census Bureau). Non-citizen rates: 2024 ACS 5-year estimates, table B05001 (U.S. Census Bureau). Current seat allocations: official 2020 Census apportionment (Census Bureau, April 2021). Comparable peer estimates: Pew Research Center (2021) · Center for Immigration Studies (2022) · UC Law Journal (2024).