The River Road Historic Rural District is a historic district located on the western side of the Millstone River along a six-mile segment of River Road / County Route 533 in Hillsborough and Montgomery Townships, Somerset County, New Jersey. It is bounded on the north by Hillsborough Road and on the south by Van Horne Road / U.S. Route 206. The district was added to the National Register of Historic Places on March 21, 1991.