West Windsor is a township in Mercer County, in the U.S. state of New Jersey. Located at the cross-roads between the Delaware Valley region to the southwest and the Raritan Valley region to the northeast, the township is considered to be an outer-ring suburb of New York City in the New York metropolitan area, as defined by the United States Census Bureau. As of the 2020 United States census, the township's population was 29,518, its highest decennial count ever and an increase of 2,353 (+8.7%) from the 27,165 recorded at the 2010 census, which in turn reflected an increase of 5,258 (+24.0%) from the 21,907 counted in the 2000 census.

Mercer County is a county located in the U.S. state of New Jersey. Its county seat is Trenton, also the state capital, prompting its nickname The Capital County. Mercer County alone constitutes the Trenton–Princeton metropolitan statistical area and is considered part of the New York combined statistical area by the U.S. Census Bureau, but also directly borders the Philadelphia metropolitan area and is included within the Federal Communications Commission's Philadelphia Designated Media Market Area. The county is part of the Central Jersey region of the state.