Which political process is necessary for redistricting?
election
census
filibuster
gerrymander

Redristricting is the method of drawing United States electoral district boundaries. In 34 states, the state legislature has main responsibility for creating a redistricting plan; Members of Congress, state legislators, and many county and municipal offices are chosen by voters grouped into districts. However once per decade, typically after a Census, district lines are redrawn, block by block. Some districts increase residents, some lose them. Some districts increase the numbers of minorities, some districts lose them. District boundaries are redrawn to safeguard each district has about the same number of people and to fulfill the constitutional guarantee that each voter has an equal say.