Article I, Section 2 of the Constitution says that “Representatives and direct Taxes shall be apportioned among the several States” according to their population. The first census was taken in 1790, directed by Thomas Jefferson. Today the census divides “the 435 memberships, or seats, in the House of Representatives among the 50 states.”
The Census Bureau calls apportionment the census’s “initial use.” Every ten years, the share of political power each state holds in the House is set by a count.