Rapidly growing populations in Western and Sun Belt states coupled with stagnant growth in Northeastern states will shift as many as 10 House seats after the 2020 Census, according to a new analysis of population trends.

The analysis, using both short- and long-term population projections by redistricting expert Kimball Brace at Election Data Services, shows seven states are likely to pick up seats in the next round of constitutionally mandated reapportionment, which follows the decennial Census.

Texas and Florida are poised to gain the most House seats. Texas will likely gain either three or four seats, depending on the rate of population growth over the next four years, while Florida is projected to add two new seats.

If the trends hold, it would continue streaks in both states – Texas has added multiple House seats the past five decades, and Florida has added at least two House spots seven cycles in a row.

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Arizona, Colorado, Montana, North Carolina and Oregon are all projected to add an additional House seat after population increases.

Oregon and Montana narrowly missed out on an additional seat last decade; both states were less than 100,000 new residents from gaining another vote in Congress.

Every 10 years, after the Census Bureau has issued population counts for all 50 states, the clerk of the House of Representatives formally notifies states of the number of seats they will hold for the next decade.

Every state is guaranteed one of the 435 voting seats in the House. The remaining 385 seats are then apportioned using a formula known as the Huntington-Hill method. The formula calculates the order in which states are allocated seats based on population until all the seats have been doled out. The 51st seat — the first to be calculated after each state is automatically given one — will go to California, the nation’s most populous state.

Eight states are projected to lose at least one spot in the House.

Because of slow population growth or population loss, most of the states poised to lose a seat are in the Northeast or the Rust Belt.

New York will lose a seat for the eighth straight decade, dropping to 26 seats in Congress after hitting a peak of 45 after the 1930 and 1940 Censuses.

Pennsylvania's delegation will likely lose one seat and narrowly hang on to another for a total of 17, after a high of 36 seats following the 1910 Census. Ohio will continue its decades-long slide, dropping from 16 seats to 15, if current trends hold.

Rhode Island is projected to lose one of its two seats, which could pit Democratic Reps. David Cicilline and Jim Langevin against each other in a primary.

West Virginia, Michigan and Minnesota are all projected to lose a seat, while Illinois is likely to lose either one or two seats, depending on late trends.

Late developments can make a significant amount of difference: Louisiana lost a House seat after the 2010 Census because of a decline in population due to Hurricane Katrina.

Wisconsin is preserving its eighth seat by a narrow margin of about 72,000 residents.

The only state outside the Rust Belt and Northeast likely to lose a seat is Alabama, whose delegation is likely to drop from seven seats to six.

Yearly population estimates released by the Census Bureau this week showed all 10 of the fastest-growing states in the union were Western or Sun Belt states. Seven of the eight states that lost population over the last year are in the Rust Belt or the Northeast.

The projections mean that, following the 2020 Census, reapportionment and redistricting process, Florida will now be the third-largest delegation in the U.S. House of Representatives. After the 2010 Census, Florida's delegation was the same size as New York's.

Minnesota won the final 435th seat in the last reapportionment process. It narrowly beat out North Carolina, which missed picking up a 14th seat by just over 15,000 residents.

Current long-term trends suggest Texas will sneak in under the line to claim the 435th seat next time around, bumping out Illinois.

This is the second decade in a row in which California will likely not gain a seat. California gained its 53rd seat in Congress after the 2000 Census, but the state has not grown fast enough to add new seats.