Final answer:
Congressional seats are reapportioned every decade to account for population changes in states, ensuring equal representation in the House of Representatives with a consistent number of 435 seats.
Step-by-step explanation:
Congressional seats are reapportioned every decade to accommodate changes in state populations after the census is taken. This is done to ensure equal representation in the House of Representatives, as the Constitution mandates a reapportionment of seats based on population data from the U.S. Census Bureau, which is conducted every ten years. With a permanent cap at 435 seats in the House, states may gain or lose seats depending on demographic shifts, thereby necessitating the redrawing of district boundaries to maintain equal population representation in each district. Reapportionment and the subsequent redistricting deal with the evolving demographic makeup of the country, transitioning from largely rural to predominantly urban, and address the changing number of constituents each representative serves, aiming to keep it around 700,000 citizens per district.