Plainsboro Township is a township situated in southern Middlesex County, within the U.S. state of New Jersey. Centrally located in the Raritan Valley region, the township is an outer-ring suburb of New York City in the New York metropolitan area, even though it is slightly geographically closer to Center City, Philadelphia than to Midtown Manhattan. As of the 2020 United States census, the township's population was 24,084, its highest decennial count ever and an increase of 1,085 (+4.7%) from the 22,999 recorded at the 2010 census, which in turn had reflected an increase of 2,784 (+13.8%) from the 20,215 counted at the 2000 census.
Plainsboro was incorporated as a township on May 6, 1919, from lands north of Plainsboro Road and Dey Road that had been part of South Brunswick Township and lands south of Plainsboro Road and Dey Road that had been part of Cranbury Township. The main impetus towards the creat