Mason was appointed as the postmaster of Sunnyside in 1867, becoming the first documented African-American postmaster in the United States. He served as a member of the
Arkansas Senate from 1868 to 1869. However, he failed to fill the position. He served in the Arkansas Senate a second time, from 1871 to 1872. He then served as the Sheriff of Chicot County from 1872 to 1874. In the summer of 1873, he was arrested under the suspicion of inciting a race war in the county. The judge, Colonel John A. Williams, dismissed the trial. ==Personal life==