Davidson was elected as a Democrat to the Forty-fifth and to the six succeeding Congresses (March 4, 1877 – March 3, 1891). He served as chairman of the Committee on Railways and Canals (Forty-eighth through Fiftieth Congresses). He was an unsuccessful candidate for renomination in 1890 to the Fifty-second Congress. He served as member of the State railroad commission in 1897 and 1898. He engaged in the practice of his profession until his death in Quincy, Florida, January 18, 1908. He was interred in Western Cemetery.