The apportionment of seats in the House of Representatives was based on the 1910 United States census.

[1] The count below identifies party affiliations at the beginning of the first session of this Congress, and includes members from vacancies and newly admitted states, when they were first seated.

Senators were elected every two years, with one-third beginning new six-year terms with each Congress.

Preceding the names in the list below are Senate class numbers, which indicate the cycle of their election.

The names of members of the House of Representatives elected statewide on the general ticket or otherwise at-large, are preceded by their district numbers.