The apportionment of seats in this House of Representatives was based on the 1870 United States census.

The House had a Republican majority; the Senate was evenly divided for the first time ever, with no vice president to break ties for most of this term.

[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 by the state legislatures 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.