It Happened in Hillsborough: Millstone Valley Agricultural Historic District

Hillsborough became serious about preserving its past around the time of the township’s bicentennial in
1971. It did this by enacting a historic preservation ordinance, adding a Historic Preservation Plan
Element to the Master Plan, and creating historic districts. There are six historic districts registered at
the state and national level: South Branch (1977), Neshanic Mills (1978), Neshanic (1979), Millstone
Valley Agricultural (1977), Clover Hill (1980), and Millstone River Road (1991). In this column, we’ll take a
look at one of these every couple of months throughout the year.

Millstone Valley Agricultural Historic District

The Millstone Valley Agricultural Historic District, which runs along River Road from the southern
boundary of the Borough of Millstone to Hillsborough Road, was entered on the State and National
Registers of Historic Places in 1977. It is different from most of Hillsborough’s historic districts in that it
is not centered on an 18 th or 19 th century village, but draws significance from its farming community.
At least that’s the way the district was interpreted in the 1970s. Two hundred years earlier, the area was
known as Schenck’s Mill, and was coveted by the British and the Americans during the Revolution. Later,
as Blackwell’s Mill, the locale grew into a vibrant 19 th -century hamlet with a school, store, post office,
and grist mill.

Because Blackwell’s Mill boasted a bridge spanning the Millstone River from its earliest days of
settlement in the 1730s, the opening of the Delaware and Raritan Canal in the 1830s played an
important role in increasing the hamlet’s prominence, both in Hillsborough and on the opposite side of
the river in Franklin Township. Agricultural prosperity also increased as farmers gained a new
dependable method of transporting their produce to market.

Unfortunately, by the middle of the 20 th century, all of the public and commercial buildings had been
lost. The last mill on the site burned down in 1905, and the schoolhouse succumbed to the same fate in
1947. Today the district includes about a dozen contributing properties; houses mostly from the early
and mid-19th century and a notable Dutch barn. Since the registry nomination a half century ago, a
couple of the houses have been moved from their original locations near Millstone River Road (and the
often-flooding river) to safer locations higher up on the west side of the road.

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Gregory Gillette has been writing about local history for 20 years, starting with his Courier News column
“Gillette on Hillsborough” and continuing today with a Facebook page of the same name. A recipient of
the Somerset County Cultural and Heritage Commission History Award for Education/Leadership in
2018, he was named as Hillsborough’s first Local Historian in 2025.