[2] He was born on August 2, 1860, in Bridgeton, New Jersey, to Charles Christopher Grosscup and Anna Dare Hires.

[2] He married Sarah E. Finlaw (1858–1884) on October 19, 1881, in Camden, New Jersey, and had as their child, Walter Truman Grosscup (1883–1950).

Grosscup had made an unsuccessful run in Cumberland County for sheriff in 1896, and lost a race for a seat in the New Jersey Senate in 1898 to Edward C. Stokes, a Republican who would later be elected as Governor.

He moved to Gloucester County in 1899, settling in Wenonah, later making an unsuccessful run for Congress, opposing Henry Clay Loudenslager.

[4] He was elected Treasurer of the State of New Jersey in 1913 replacing Daniel Spader Voorhees.