James Wilson Marshall, of English descent, was born to Philip Marshall and Sarah Wilson (married 1808) at the family homestead in Hopewell Township, New Jersey (then part of Hunterdon County, New Jersey, currently part of Mercer County) on October 8, 1810. The family homestead was known as the Round Mountain Farm and is still known as Marshalls Corner. He was the oldest of four children, and the only male. In 1816, the Marshall family relocated to nearby Lambertville, where Philip constructed a house on approximately five acres of land.