After the decennial Census is completed, states are apportioned a certain number of congressional districts based on population. Redistricting is the process undertaken by individual states where new district boundaries are created, each with an equal population. See the article Who Draws the Lines? for more details about the process followed in each state.

The most recent redistricting took place after the 2020 Census. The new boundaries were used for the 2022 midterm elections and went into effect when the new House was seated in January, 2023.