The family includes Andrew Mellon, one of the longest serving U.S. Treasury Secretaries, along with famous members in the judicial, banking, financial, business, and political professions.

The American branch of the Mellon family traces its origins to County Tyrone, Northern Ireland.

In 1816, Archibald Mellon emigrated from Northern Ireland to the United States and set up residence in Westmoreland County, Pennsylvania.

Under the direction of Thomas's son, Andrew William Mellon, the Mellons became principal investors and majority owners of Gulf Oil (which merged with Chevron Corporation in 1985), Alcoa (since 1886), The Pittsburgh Tribune-Review (since 1970), Koppers (since 1912), New York Shipbuilding (1899–1968) and Carborundum Corporation,[2] as well as their major financial and ownership influence on Westinghouse Electric,[3] H.J.

The family's founding patriarch was Judge Thomas Mellon (1813–1908),[4] the son of Andrew Mellon and Rebecca Wauchob, who were Scotch-Irish farmers from Camp Hill Cottage, in Lower Castletown, County Tyrone, Ireland, and emigrated to what is now the Pittsburgh suburb of north-central Westmoreland County, Pennsylvania.