This is a complete list of United States senators during the 79th United States Congress listed by seniority from January 3, 1945, to January 3, 1947.
Order of service is based on the commencement of the senator's first term. Behind this is former service as a senator (only giving the senator seniority within their new incoming class), service as vice president, a House member, a cabinet secretary, or a governor of a state. The final factor is the population of the senator's state.
Senators who were sworn in during the middle of the two-year congressional term (up until the last senator who was not sworn in early after winning the November 1946 election) are listed at the end of the list with no number.
In this Congress, Richard Russell was the most senior junior senator. The distinction of most junior senior senator passed between four different individuals in this Congress, due to various deaths and resignations: Guy Cordon, from January 3 to 10, 1945; Warren Magnuson from January 10 to 17, 1945; Forrest Donnell from January 17 to November 10, 1945; and Glen Taylor from November 10, 1945 through the end of the 79th Congress.
The most senior senators by class were Kenneth McKellar (D-Tennessee) from Class 1, Arthur Capper (R-Kansas) from Class 2, and Walter F. George (D-Georgia) from Class 3.