Born in Bath, Maine, little is known of Prior's early education or work as an artist. His first portrait painting is recorded during 1823, although he was advertised as a sign, ornamental painter and decorator. His portraits ranged in lower prices, which demonstrated his flexibility in satisfying his customers' needs and limitations. Prior is frequently associated with his brother-in-law, Sturtevant J. Hamblin, and thus, artists whose works are executed in a similar style and manner are known as the "Prior-Hamblin School."