Because Clovis-type spear points have been found in Hillsborough, we must believe that early man arrived at least ten or twelve thousand years ago when the mammoth and mastodon still roamed the area. Artifacts of all of the archaeological periods are present, which indicated continuous occupation until historic times.

Hillsborough and the surrounding area were first explored by the Dutch in the middle 17th century. At that time the area was occupied by the Unami Indians who were a part of the Lenapi Tribe. Because they spoke the Algonquin language they were considered part of the Algonquin Nation.

Records of the Proprietors and Reeds map of 1685 show that large tracts of land were patented to shareholders in the Proprietorship at a very early date. Some of the earliest land transactions found in the records of Hillsborough begin around 1700 and include the names John Royce, Peter DuMont and Hendrik Beekman. Some of this land lies along what is now South Branch River Road. A short time later farms were carved out of a tract patented to Thomas Barker, whose land was along the Millstone River.

In 1676 West Jersey, including the area of Neshanic and South Branch, was sold to William Penn. In 1710 a large interior tract, known as the “Harlingen Tract,” was sold to Dutch investors by Peter Sonmans. A parcel of this tract was set aside for a parsonage lot, but was not used until after the Harlingen Church organized in 1727. Grist mills were one of the earliest industries. Records of mills in the Neshanic area go back to 1692 and perhaps earlier. As early as 1746 a mill was recorded along the Millstone River.

Hillsboroughs roads got their names from early records, Hillsborough was also known as Hillsbury and although the records are obscure, some believe the Township was named for Lord Hillsborough.

Hillsborough received its Charter on May 29, 1771, and officially became Hillsborough Township. Before that date it was known as the “Westering Precinct of Somerset County”.

Hillsborough Township celebrated its 250th in 2021. It was a time to celebrate the history and progress of the community. With that in mind, the municipality hosted a variety of commemorative activities and events, including a parade, scarecrow festival, fireworks, various contests and limited edition merchandise available for purchase throughout the year.