hill was elected on august 14, 1923, as u.s. representative from alabama's 2nd congressional district to fill the vacancy created by the death of john r. tyson. he served as chairman of the house committee on military affairs. on january 10, 1938, hill was appointed to the u.s. senate to fill the vacancy caused by the resignation of senator dixie graves for the term ending january 3, 1939. hill was subsequently elected to the senate as a democrat on april 26, 1938. he was reelected in 1944, 1950, 1956, and 1962. he retired in january 1969.