 Dixon was elected as a representative of Connecticut's 1st District, as a Whig to the House, serving during the Twenty-ninth and Thirtieth Congresses (March 4, 1845 – March 4, 1849), and was a member of the State house of representatives in 1854.He declined the nomination for Governor of Connecticut in 1854, and was an unsuccessful candidate for United States Senator in 1854.Dixon was elected as a Republican to the U.S. Senate in 1856, and reelected in 1863, serving from March 4, 1857, to March 4, 1869.