Temporarily apportioned two House seats each for the newly admitted states of Kentucky and Vermont, until their populations were included in the upcoming post-census reapportionment.

Increased the ratio from the one House member for every 30,000 residents, the proportion set by the Constitution, to one for every 33,000 residents; there were 105 seats in the House of Representatives. Apportioned seats among the states using the Jefferson method.

The ratio remained one House member for every 33,000 residents, although the size of the House of Representatives was increased to 142 seats. Seats were apportioned among the states using the Jefferson method.

Set a ratio of one representative for every 35,000 residents, with a House size of 181 seats. The Jefferson method was used to apportion seats.

Divided Massachusetts's House delegation so that those who had represented the territory of the new state of Maine now comprised Maine's House delegation. In the elections of 1820, Massachusetts was to elect thirteen representatives, and Maine was to elect seven.

Set the ratio to one representative for every 40,000 residents. The size of the House of Representatives is increased to 213 seats, and the apportionment was made, once again, using the Jefferson method. The 1820 reapportionment was the first time states lost House representation in absolute terms.

Awarded Alabama an additional (third) seat in the House of Representatives.

Set the ratio to one member of Congress for every 47,700 residents. Increased the size of the House of Representatives to 240 seats. The Jefferson method was again used to apportion seats among the states, but delegation from the smaller states, led by John Quincy Adams of Massachusetts, strenuously objected and pushed for the Webster method to be used instead.