Each decade, the federal government compiles and publishes updated population figures for all 50 states in a census required by the U.S. Constitution. Seats in the U.S. House of Representatives are then awarded, with some states gaining or losing seats while others retain the same amount. In either case, states must redraw their district lines to make sure each district contains roughly the same number of people.
Redistricting has become a highly politicized process as parties jockey for advantage in the midterms to determine control of the narrowly divided House. Where the lines are drawn can heavily favor one party over the other.
Adrian Blanco, Ted Mellnik and Harry Stevens contributed to this report.