Monmouth Junction is an unincorporated community and census designated place (CDP) located within South Brunswick, in Middlesex County, in the U.S. state of New Jersey. As of the 2010 United States Census, the CDP's population was 2,887.

South Brunswick is a township in Middlesex County, in the U.S. state of New Jersey. The township is centrally located within the Raritan Valley region and is an outer-ring suburb of New York City in the New York metropolitan area. As of the 2020 United States census, the township's population was 47,043, its highest ever decennial census count and an increase of 3,626 (+8.4%) from the 2010 census count of 43,417, which in turn reflected an increase of 5,683 (+15.1%) from the 37,734 counted in the 2000 census.