Samuel Anderson Purviance was born in Butler, Pennsylvania. He entered college and pursued a partial course and then studied law. He was admitted to the bar in 1827 and commenced practice in Butler. He moved to Warren County, Pennsylvania, and was prosecuting attorney for two years. He returned to Butler, where he continued the practice of law. He was a delegate to the state constitutional convention of 1837 and 1838. He was a member of the Pennsylvania House of Representatives in 1838 and 1839. He was a delegate to the 1844 Whig National Convention and to the Republican National Convention in 1856, 1860, 1864, and 1868.