Illinois peaked at 27 U.S. House seats after the 1910 Census and subsequent reapportionment. That lasted until the 1940 Census, when Illinois dropped to 26 seats in Congress. We’ve been steadily losing ground ever since. It’s not that we lost population, it’s that other states in the West and the South grew much faster. California had just eleven congressional districts as a result of the 1910 Census. It now has 53.