This biography from the Archives of AskART:
Born in Lancaster, Pennsylvania, he trained as a coppersmith and had no formal art trainting. Thomas Sully, a leading portrait painter was a major influence on his work. Between 1810 and his death in 1842, he painted more than 850 portraits as well as some landscapes and history paintings. His specialty was strong, linear portraits of prominent people in the Philadelphia and Baltimore area. Among his subjects were Chief Justice John Marshall and Nicholas Biddle, president of the Bank of the United States. He was financially successful.