What occurs every 10 years that sets reapportionment of House seats into motion? Head count of the Senators The Census Hailey's Comet Adding a new state IRS Tax Audit

The Census<br /><br />The United States conducts a national census every 10 years, which is used to determine the population of each state. This data is then used to reapportion the seats in the House of Representatives among the states based on their population.