The apportionment of seats in the House of Representatives was based on the 1850 United States census.

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.

The names of members of the House of Representatives are preceded by their district numbers.

The count below reflects changes from the beginning of the first session of this Congress.