Born in Philadelphia, Pennsylvania. At age 21, on the death of his father, he became manager of the family business and administrator of the estate. Married Henrietta Boude May 10, 1753. They had ten children. He was a member of the Masons in Philadelphia.

He was a member of the provincial Assembly of Pennsylvania 1765 to 1775. Hillegas and George Clymer served jointly as the first Continental Treasurer of the United States serving July 29, 1775, to August 6, 1776. Clymer resigned to serve in Congress and Hillegas became the sole Continental Treasurer until September 6, 1777. At that time he was appointed Treasurer of the United States and served until September 9, 1789.

When anthracite coal was discovered in Pennsylvania, Hillegas joined others in the formation of the Lehigh Coal Mining Company. He was elected alderman in Philadelphia and served from 1793 until his death in Philadelphia.

Hillegas appears on paper money: $10 Gold Certificate, series 1907 and 1922

bio: *ApCAB; DAB; Drake; Limpert; *NCAB 11; TCBDA; WWW-H (*give date as 1728)