 Upon crossing the Millstone River, Route 27 runs along the border of Franklin Township, Somerset County to the west and South Brunswick Township, Middlesex County to the east, passing through the historic community of Kingston.It continues northeast through a mix of woodland and residences, intersecting Promenade Boulevard, which heads east and becomes County Route 522 after crossing U.S. Route 1.Route 27 briefly runs entirely into Somerset County before resuming along the Middlesex/Somerset County border.