How Congressional Seats Are Divided Among the States

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After the 2020 census, Texas picked up two seats in the U.S. House of Representatives. California lost one for the first time in its history. New York missed keeping a seat by, according to the Census Bureau, a margin of 89 people.

None of this was a vote. No senator negotiated it. A formula did.

The short answer runs like this: every ten years the country counts its population, and a fixed pool of 435 seats gets handed out among the 50 states by a mathematical rule called the method of equal proportions.

Whether your state gains or loses a seat depends on one thing above all: how fast it grew compared to everyone else. You can add population and still lose a seat, if your neighbors added more.

The rules themselves are stable and old. What surrounds them, who gets counted, whether 435 is still the right number, is anything but settled.

The Constitution Ties Seats to People, Not Land

The whole system starts with a single sentence in Article I, Section 2. The Constitution says representatives “shall be apportioned among the several States… according to their respective Numbers,” and requires an “actual Enumeration” every ten years.

Two ideas are packed in there. Representation follows population, not acreage or wealth. And the count has to happen on a clock: once per decade, forever.

The Constitution left the mechanics to Congress. That is why the method for dividing seats has changed several times, and why the size of the House was never fixed in the founding text. The first House had just 65 members.

After the Civil War, the Fourteenth Amendment restated the principle with sharper language. Section 2 apportions seats “counting the whole number of persons in each State, excluding Indians not taxed.”

That phrase, whole number of persons, does a lot of work. Legal scholar Joseph Fishkin sees it as proof of the Constitution’s commitment to universal representation: everyone in the community is represented, whether or not they can vote. That reading matters because it shapes who gets counted, a fight we will get to.

Section 2 also carries a rarely discussed set of teeth: a Penalty Clause that reduces a state’s representation if it denies the vote to eligible male citizens except for participation in rebellion, or other crime. Fishkin notes it has almost never been enforced, and Congress has not used it to strip seats for modern voting-rights violations. It stays in the text as a threat that has never really been used.

Why the House Is Frozen at 435

For over a century, the House simply grew. As the population climbed and new states joined, Congress kept adding seats so no state had to lose one just because the country got bigger.

Then the growth stopped. After the 1910 census, Congress set the House at 433, with two seats held for Arizona and New Mexico, reaching 435 in 1913. Around then, the average district held about 210,000 people.

The 1920 census broke the pattern. Rural representatives, watching population pour into cities, refused to pass any reapportionment at all. Congress deadlocked for an entire decade. The American Redistricting Project calls it a period of legislative paralysis, and the stakes were constitutional: the country was ignoring its own enumeration.

The fix came in the Permanent Apportionment Act of 1929, enacted June 18 of that year. Its title is drier than its effect: “To provide for the fifteenth and subsequent decennial censuses and to provide for apportionment of Representatives in Congress.”

The Act did two things that still govern today. It capped the number of representatives at 435, the size set back in 1911. And it automated the process, so seats get redistributed after each census without Congress passing a new law.

The detail worth sitting with: the number 435 was not chosen for any principle of representation. As the American Redistricting Project puts it, “The 435-seat House of Representatives is not a number derived from constitutional wisdom or democratic theory. It is a historical accident, the legislative fossil of a political crisis that occurred a century ago.” Congress picked stability over a fight it could not win.

The cap did wobble once. When Alaska and Hawaii joined in 1959, the House briefly ran at 437 seats, then snapped back to 435.

Who Counts, and Where the Census Draws Its Lines

Before any seats can be divided, the Census Bureau has to decide who goes into the pile.

The timing is set by law. Federal law pegs Census Day to April 1. The Bureau then has nine months to deliver apportionment counts to the President. The President reports them to Congress within a week of the next Congress convening, and the Clerk of the House then has fifteen days to tell each governor how many seats their state gets.

What goes into the apportionment population? The total resident population of the 50 states, citizens and noncitizens alike, plus U.S. military and federal civilian employees stationed overseas (and their dependents), assigned back to a home state.

What stays out: the District of Columbia and Puerto Rico, because neither has voting seats in the House. The Iowa State Data Center notes the “resident population” used for apportionment also excludes foreign diplomats and temporary visitors. So where someone officially “lives” for apportionment is a legal definition, not a headcount of everyone standing on the soil.

The overseas-employee rule has been litigated before. In Franklin v. Massachusetts, a district court had ordered the Secretary of Commerce to “eliminate the overseas federal employees from the apportionment counts” and directed a new presidential statement, but the Supreme Court reversed, finding no final agency action reviewable under the APA. Seemingly minor, paperwork-level choices about who counts can move real seats, which is why they end up in front of judges.

One more twist for D.C.: it gets no voting House member, yet the Twenty-Third Amendment gives it three electors and treats it like a state for the Electoral College. Represented in the presidential math, absent from the House math.

The Formula That Divides the Seats

Once the population numbers are locked, the division is pure arithmetic. Since 1941, Congress has required the method of equal proportions, also called the Huntington-Hill formula after the two statisticians behind it, Edward V. Huntington and Joseph A. Hill.

The goal, in the Census Bureau’s words, is “to minimize the relative (or percentage) differences in representation (the number of people per representative) among the states.” Plainly: get the people-per-seat ratios as close together across states as the numbers allow.

The mechanics run like this. Every state gets one seat off the top, the constitutional minimum. That leaves 385 seats to hand out.

For each state, the Bureau computes a “priority value” for its second seat, third seat, fourth, and so on, by dividing the state’s population by the geometric mean of the current and next seat numbers. Then it lines up all the priority values from every state, sorts them highest to lowest, and awards the 385 remaining seats to the top 385 values.

Picture two states. Call one Alpha, with 10 million people, and one Beta, with 5 million. Alpha’s priority value for a second seat comes out exactly twice Beta’s, because Alpha has twice the people and the divisor is identical.

So Alpha’s second seat lands higher on the sorted list and gets awarded first. As a state accumulates seats, its divisor grows, its priority values shrink, and eventually a smaller state’s next seat outranks a big state’s.

The scale is larger than you might guess. For 2020, California was the most populous state, so the Bureau calculated priority values for potential seat numbers 2 through 70 for every state, producing 3,450 values to sort. Only the top 385 got a seat.

That is the whole engine. No negotiation, no discretion, just population divided by a square root, sorted and cut off at 385.

What the 2020 Numbers Did

The 2020 apportionment population for the 50 states came to 331,108,434, announced at a Census Bureau news conference on April 26, 2021. (The more widely reported figure of 331,449,281 is the resident population that includes the District of Columbia, which gets no House seat.) Thirteen states saw their delegation change.

Here is where the seats moved.

States that gained or lost U.S. House seats after the 2020 census

Source: U.S. Census Bureau, 2020 Census apportionment results.

The result: Texas now sends 38 representatives, California 52, and New York 26. Because a state’s electoral votes equal its House seats plus its two senators, those shifts ripple straight into presidential math. The National Archives puts it simply: electoral votes are “allocated among the States based on the Census.” The 2020 allocations govern the 2024 and 2028 elections.

The Fight Over Counting Undocumented Immigrants

If seats follow the whole number of persons, a natural question follows: which persons? In 2020 that question turned into a genuine legal war.

A memorandum’s policy line was blunt: to exclude from the apportionment base aliens who are not in a lawful immigration status, to the extent feasible.

Proponents made a real argument, not a throwaway. Attorney General William Barr defended the memo by pointing to presidential authority under the apportionment statute. Scholars like John Eastman, then at Chapman University, argued that founding-era terms like “inhabitant” and “persons” were meant to track lawful membership in a state’s community, not mere physical presence.

Hans von Spakovsky of the Heritage Foundation argued that counting undocumented residents dilutes citizen equality and skews the Electoral College. Mark Krikorian of the Center for Immigration Studies framed it as an incentive problem: counting everyone rewards states that tolerate illegal immigration.

Twenty states, cities, and localities sued, arguing the memo violated the constitutional and statutory command to count all persons, and that it was driven by bias against Hispanic and immigrant communities.

On September 10, 2020, a three-judge court in the Southern District of New York blocked the memo, holding it violated the federal laws governing the census and apportionment.

The administration appealed straight to the Supreme Court, which wiped that ruling away on December 18, 2020, though not on the merits. In Trump v. New York, the Court vacated the lower court’s order and directed the case be dismissed, finding the dispute premature: it was not yet clear whether the Commerce Secretary could actually carry out the exclusion, or how many people it would touch. The justices pointedly declined to say whether the policy was lawful.

In the end the point stopped mattering anyway. The administration could not produce the exclusion before the December 31 statutory deadline, and on his first day in office, President Biden rescinded the memo by executive order. The Bureau transmitted counts that included noncitizens, as it always had.

A related fight had already reached the Court, where the administration tried to add a citizenship question to the census. Chief Justice John Roberts held that the Secretary “is authorized to take a decennial census of population… in such form and content as he may determine,” so a citizenship question was not itself unconstitutional.

But he blocked this one, because “the evidence tells a story that does not match the explanation the Secretary gave for his decision.” The Voting Rights Act reason the administration gave was only an excuse, and the Court sent it back, ruling the decision was made without a good enough reason.

Should the House Grow Past 435?

Because 435 is a statute, not a constitutional command, Congress could change it tomorrow.

The main complaint from people who want change is that a frozen House plus a guaranteed minimum seat per state hands small-state residents more representation per person than large-state residents. A Brookings Institution analysis argues the equal-proportions method “systematically” over-represents small states, and recommends returning to the older Webster method.

The most-discussed fix is the Wyoming Rule: set the size of a typical district to match the smallest state’s population, then give every state seats to match. Advocates like the transparency of the pitch, roughly, every representative should serve about as many people as the one from Wyoming.

Others go further. The American Academy of Arts and Sciences, in its “Our Common Purpose” report, has also urged enlarging the House.

By that yardstick, the American House is unusually small.

The case for leaving 435 alone is quieter, and mostly institutional. It rests on governability: a much larger chamber means more coalitions to manage, more committee seats to fill, and more pressure to hand power to leadership just to keep the floor moving.

The comparison cuts both ways, too. The U.K. Commons runs 650 members for about 67 million people; Germany’s Bundestag runs larger still, and neither is a model of frictionless deliberation.

Honest note: the pro-435 side has few dedicated champions. The intellectual energy is on the side of enlargement.

Apportionment Is Not Redistricting, and Neither Is Gerrymandering

People blur three separate things, and the blur causes real confusion. It is worth pulling them apart.

Apportionment decides how many seats your state gets. That is the Census Bureau’s formula, and it is done the moment the counts are transmitted.

Redistricting is what happens next inside your state: legislators or commissions draw the actual district lines. Federal law requires those districts to hold substantially equal populations, a rule that flows from the Supreme Court’s “one person, one vote” decisions. If your state goes from seven seats to eight, mapmakers have to carve eight roughly equal districts.

Gerrymandering is the manipulation of those lines for partisan advantage. It lives entirely inside redistricting, governed by a different body of law, including the Voting Rights Act.

So the sequence is clean even when the politics are not. Apportionment answers how many, redistricting answers where, and gerrymandering is one contested way the “where” gets drawn.

When you see headlines about census seat counts, that is apportionment. When you see fights over oddly shaped maps, you are looking at the stage after.

What 2030 Is Already Setting Up

The next reckoning is closer than it feels. The 2030 census will reshuffle the same 435 seats, and the early projections point in a familiar direction.

The Brennan Center’s latest projections, drawing on Census Bureau estimates released in early 2026, suggest the South could gain as many as nine House seats after 2030 — the region’s largest single-decade gain on record — pushing its share toward nearly four in ten members and a record 164 seats. Texas and Florida lead the expected gainers, with North Carolina and several mountain states also in line to pick up seats, while California could lose as many as four. Those are projections, not settled fact — the Brennan Center stresses the numbers hinge heavily on future immigration levels, and Florida’s projected gain has already shrunk as its growth cooled — but the underlying trend of Sun Belt growth is well documented.

Which sets up the real tension the formula cannot resolve. Every seat a fast-growing state gains, a slower-growing one loses, because the pool never changes. As long as the House stays at 435, apportionment is a zero-sum game played on a fixed board, and the board is starting to tilt hard toward one region.

That question is worth watching between now and 2031. Not whether the math will work; it always does. It is whether a country that has doubled in population since 1929 will keep dividing the same 435 chairs, or finally reopen the fight Congress walked away from a century ago.

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