Apportionment is the most important function of the decennial census. Apportionment measures the population so that seats in the U.S. House of Representatives can be correctly apportioned among the states. This map shows the apportionment of the U.S. House of Representatives based on the 2010 Census. Each state is marked with the number of delegates it received to the U.S. House of Representatives and is color-coded depending on it gained, lost, or had an unchanged number of seats from 2000.