How the Census Apportions Seats

The method of reapportionment has changed four times in the 229 years following its inception, but the data for it has always come from a decennial national census. The method we use today is known as the Method of Equal Proportions and was first used in 1941. It utilizes a formula that assigns seats based on a priority value until all 435 members are allotted. The number of seats in Congress (435) was set by a federal statute in 1911 and has remained constant – aside from temporary districts for Alaska and Hawaii in 1959.

Current Apportionment and Recent Trends

The Census Bureau last allocated Congressional seats on December 21, 2010.

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Reapportionment sent 11 seats from the Northeast and Midwest to the South and West in 2010.

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Ten years earlier, a similar 10-seat transfer occurred. The changes so far in the 21st Century have resulted in New York losing 4 members, Ohio and Pennsylvania each losing 3, and Michigan and Illinois both dropping 2. Over the same period, Texas increased by 6 members, Florida by 4, Arizona and Georgia by 3 each, and Nevada by 2.

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