Redistricting multiple choice happens every 4 years. is conducted by state legislatures. must be approved by congress. must be approved by the highest court in each state. has little appreciable effect on who wins or loses congressional races.

In most states, the State Legislatures have control over redistricting. It can have a significant effect on Congressional races, as often the two major parties seek to draw lines that maintain or increase their control by combining areas that support them, and trying to divide areas that support their opponents.