435 This question isn't quite accurate. The size of the United States House of Representatives was capped to 435 by the Apportionment Act of 1911, which is otherwise known as "Public Law 62-5". Even with the 435 member cap, the size of the House of Representatives did climb temporarily past the cap when Arizona, New Mexico, Alaska, and Hawaii joined the United States and went back down to 435 after the next reapportionment was made in each case.