The apportionment of seats in the House of Representatives was based on the 1880 United States census.

The Republicans maintained a majority in the Senate (albeit reduced), but the Democrats won back the majority in the House, ending the Republican overall federal government trifecta.

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.

The directory after the pages of terms of service lists committees of the Senate, House (Standing with Subcommittees, Select and Special) and Joint and, after that, House/Senate committee assignments.