The apportionment of seats in the House of Representatives was based on the 1940 United States census.

Along with President Franklin D. Roosevelt, the Democrats maintained an overall federal government trifecta.

[1] Section contents: Senate: Majority (D), Minority (R) • House: Majority (D), Minority (R) Senators are popularly elected statewide 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, In this Congress, Class 3 meant their term ended with this Congress, facing re-election in 1944; Class 1 meant their term began in the last Congress, facing re-election in 1946; and Class 2 meant their term began in this Congress, facing re-election in 1948.

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