Final answer:
Redistricting usually happens every ten years so that it aligns with the new U.S. Census results.
Step-by-step explanation:
Redistricting usually happens every ten years so that it aligns with the new U.S. Census results. The boundaries of legislative districts are redrawn as needed to maintain similar numbers of voters in each while still maintaining a total number of 435 districts. This process is necessary because population can change over time, and redrawing district boundaries ensures that each district has nearly the same population.