The apportionment of seats in the House of Representatives was based on the 1810 United States census.

The count below identifies party affiliations at the beginning of the first session of this congress.

During this congress, two Senate seats were added for each of the new states of Alabama and Maine.

For the beginning of the next congress, six more seats from Massachusetts would be reapportioned to Maine.

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.