Portrait and miniature painter, William Clarke was active in Lancaster County, Pennsylvania circa 1785. In the 1790’s he was active in Delaware and Baltimore, Maryland. He then worked in Philadelphia at the two firms: Pratt, Rutter & Co.; and Paul, Rutter & Clarke from 1796 to 1806. Working there, Clarke was associated with Jeremiah Paul, Matthew Pratt, and George Rutter.
Groce and Wallace, “The New York Historical Society’s Dictionary of Artists in America”
Peter Falk, “Who Was Who in American Art”