Philadelphia merchant and civic leader.

Employed by Baynton, Wharton & Morgan to visit trading posts in western Pennsylvania and Ohio (1766). Member of the American Philosophical Society (1768); treasurer (1779), councillor (1781). Director of the Library Company (1771-76). Quartermaster of the first battalion of Philadelphia Associators (1775). Marshal of the Pennsylvania Court of Admiralty (1776-80). Continental loan officer and auditor (1777-78). Elected to Congress (1785) but did not serve. Alderman (1790-98). Mayor of Philadelphia (1792-96). Director of the Bank of the United States.

Son of Matthew and Cornelia (DePeyster) Clarkson; stepson of Gilbert Tennent. Brother of Gerardus Clarkson. Married Mary Boude (1753); nine children.