# Apportionment Act of 1911 The statute that first set the size of the U.S. House of Representatives at 435 members, following the 1910 census. It enlarged the House from 391 seats and provided that Arizona and New Mexico would each add a seat on admission, bringing the chamber to its present 435. The 1911 act was ordinary decennial legislation of the kind Congress had passed after every census since 1792, and it did not purport to freeze the chamber permanently. What made 435 durable was the failure to reapportion at all after the 1920 census — the only such failure in American history — and the [[Permanent Apportionment Act of 1929]], which locked the size in place and made reapportionment automatic. Because the cap originates in ordinary statute rather than constitutional text, a simple majority of Congress can change it. See [[How the Census Apportions Congress]] and [[Wyoming Rule]]. > [!note] Stub — fill out > This page was created as a stub during learning-module generation on 2026-09-12. Audit and expand when convenient.