The Census Bureau will make the official 2020 state population numbers public in April. With that release will come reapportionment, which uses a formula to redistribute each state's share of the 435 House of Representative seats starting in the 2022 midterm election. That formula takes state population into account. Any change in that representation would have a political effect, notably in the Electoral College, where states are allotted electoral votes based on the number of members in Congress.

State redistricting comes next. By September 30, the Census Bureau will have provided each state with more granular population data separated into geographies like counties, cities, American Indian areas, census blocks, and voting districts. Any state allotted more than one representative will have to draw new maps splitting their states into geographic areas with equal populations. Each state's process and rules are different, with some of the maps drawn entirely in the legislature and others developed by independent commissions.

Here’s how reapportionment and redistricting may play out ahead of November 2022.

Population estimates suggest 15 states will lose or gain House seats.

Annual estimates from Census Bureau surveys beyond the decennial census can give a sense of how the population has shifted since 2010. Even so, only the official 2020 count will matter for reapportionment. Based on July 2020 estimates, eight states are expected to lose at least one seat. New York would lose two, while California, Illinois, Michigan, Minnesota, Ohio, Pennsylvania, Rhode Island, and West Virginia would lose one.

On the other end, Texas would gain three seats, Florida would gain two, and Arizona, Colorado, Montana, North Carolina, and Oregon would all gain a single seat.

Based on estimates, Texas would gain three House seats while New York would lose two.

Expected change in US house seats based on July 1, 2020 population estimates

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The electoral map changes with reapportionment.

The congressional seats apportioned in the census count have a direct impact on the presidential electoral process, where each state has an electoral vote for each of its members of the House and its two Senators. (The exception is Washington, DC, which has three electoral votes but does not participate in reapportionment or have voting members in Congress.)

In the 2020 presidential election, Democrat Joe Biden won with 306 electoral votes to Republican Donald Trump's 232. If every state voted the same way in 2024, Democrats would have five fewer electoral votes than they had in 2020, though they would still win 301 to 237.

For a deeper understanding for a role the electoral college played in 2020, click here.

There are rules for the redistricting process. Even if no seats change during reapportionment, every state with more than one seat will go through the redistricting, or a redrawing, of its congressional districts.

Every state must adhere to the Voting Rights Act for redistricting, ensuring each district has approximately the same population. The shapes of these districts are redrawn using population data provided by the Census Bureau that includes summary information of racial and ethnic breakdowns and the number of people living in group quarters like prisons.

While this piece primarily addresses congressional redistricting, the same data is used to redraw state legislative districts.

Many states have constitutional or legal guidelines for what they must consider in drawing congressional districts. Among the considerations:

  • Thirty-three states require geographically "compact" districts.
  • Thirty-seven states require that all land in the districts be "contiguous."
  • Thirty-three states require that districts not separate political subdivisions like counties unless necessary.
  • Twenty-three require districts to consider "communities of interest," which could include everything from racially alike groups or socioeconomically alike groups.

These considerations may be up for interpretation by the bodies drawing the maps.

Legislature-based

In most states, the state legislature has authority over the drawing and approval of maps. In some states, the new districts are approved via regular legislation and subject to a governor’s veto. In others, like Connecticut and North Carolina, the maps are not subject to governor’s approval.

Next year, 17 states will have maps drawn in Republican-controlled legislatures with and approved by a Republican governor. If 2020 population estimates hold, these states would have 165 seats, 38% of all House seats. These states had 162 seats following the 2010 reapportionment.

Eight states will draw maps in Democrat-controlled legislatures where either there is a Democratic governor or the maps will not be subject to gubernatorial veto. Combined, they accounted for 75, or 17%, of the seats in the last decade. This group of states is expected to lose two seats.

Independent commission

Nine states will have an independent commission create maps not subject to legislative approval: Arizona, California, Colorado, Hawaii, Idaho, Michigan, Montana, New Jersey, and Washington. (Montana currently has a single seat; it is expected to gain a second seat following reapportionment.)

House districts in nine states will be remapped by independent commissions.

States with and without independent redistricting commissions

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These states accounted for 110 of the 435 seats in Congress for the last decade. Based on population estimates, this group will have 111 House seats in 2022, 26% of the total.

The state commissions take different forms. For example, Arizona’s is composed of two Democrats, two Republicans, and led by an independent. Michigan’s commission members are chosen from an application pool in a multiple-step process that includes random selection.

No need for map drawing

Six states – Alaska, Delaware, North Dakota, South Dakota, Vermont, and Wyoming – will likely remain at one House seat, leaving no need for a reapportionment process for congressional seats. State legislative seats are still subject to reapportionment. Rhode Island is expected to lose its second seat and join that group.

The maps drawn for 2022 may not carry through the entire decade.

Some states maps may face legal challenges for allegations of gerrymandering — the practice of redistricting for the sake of political gain. In recent years, the Supreme Court has heard gerrymandering cases that involved Wisconsin, Maryland, and North Carolina.

In the 2019 North Carolina case, the Supreme Court ruled in a 5-4 decision that “partisan gerrymandering claims present political questions beyond the reach of the federal courts.” The ruling suggests that any cases involving political gerrymandering would occur in state courts.

Reapportionment and redistricting have significant implications for both political control and representation. The most significant changes will occur before the 2022 election, but the maps are worth watching through the entire decade for subsequent changes.