Senators were elected over a wide range of time throughout 1816 and 1817, and a seat may have been filled months late or remained vacant due to legislative deadlock.

The new state of Indiana elected its first two senators, both Democratic-Republicans, James Noble and Waller Taylor.

Robert Goodloe Harper won election over John Thomson Mason by a margin of 1.12%, or 1 vote, for the Class 1 seat.

[26] Alexander Contee Hanson won election over William Winder by a margin of 8.24%, or 7 votes, for the Class 1 seat.

[27] The new state of Mississippi elected its first two senators, both Democratic-Republicans, Walter Leake and Thomas H. Williams.