Apportionment, Reapportionment, & Redistricting

Districts for national elections are statewide and congressional.

Census Bureau:

"The U.S. Census Bureau provides the 50 states, the District of Columbia, and Puerto Rico with population counts to use in their redrawing of congressional and state legislative district boundaries—a process known as “redistricting.”

While the states are responsible for legislative redistricting, the Census Bureau provides population counts for the geographic areas the states need." "