The 63rd Congress was the first to have 435 Members. The Permanent Apportionment Act of 1929 capped the Membership at that level, creating a procedure for reapportioning state delegations in the House under “the then existing number of Representatives” (see Act of June 18, 1929, Ch. 28, 46 Stat 21).

The admission of Alaska and Hawaii into the Union as states in 1959 serves as the last example of the addition of new voting Members to the US House of Representatives. Congress temporarily added one new Representative for each state in the 86th and 87th Congresses (1959-1963), bringing the total number of Representatives in the House to 437. In 1963, when the apportionment mandated by the 18th Census (1960) took effect, the total number of Representatives in the House returned to 435 for the 88th Congress (1963-1965). For Alaska, the 49th State, the bill was H.R. 7999 which became Public Law 85-508 on 7 July 1958 (increasing to 436 temporarily) and for Hawaii, the 50th State, the bill was S. 50 which became Public Law 86-3 on 18 March 1959 (increasingly to 437 temporarily). Thus for the 86th and 87th Congress, the House had its membership temporarily increased to 437 Representatives.

The first Representative from Alaska was Representative Ralph J. Rivers (D-AK) and the first Representative from Hawaii was Representative Daniel K. Inouye (D-HI).