smart was appointed postmaster in camden in 1838. he was elected a member of the maine state senate. he was appointed aide-de-camp with the rank of lieutenant colonel on the staff of governor fairfield in 1842. smart moved to missouri in 1843 and continued the practice of his profession. he returned to camden the following year and resumed the practice of law, and was again appointed postmaster. he was elected as a democrat to the thirtieth congress (march 4, 1847 – march 3, 1849) and to the thirty-second congress (march 4, 1851 – march 3, 1853).