West Windsor is a township in Mercer County, New Jersey, in the United States. The township is part of the New York metropolitan area as defined by the United States Census Bureau. As of the 2010 United States Census, the township's population was 27,165, reflecting an increase of 5,258 (+24.0%) from the 21,907 counted in the 2000 Census, which had in turn increased by 5,886 (+36.7%) from the 16,021 counted in the 1990 Census.West Windsor and adjacent East Windsor Township were established by an act of the New Jersey Legislature on February 9, 1797, and incorporated on February 21, 1798, as two of the state's initial group of 104 townships, by partitioning provincial Windsor Township.The Borough of Princeton (now part of Princeton) was formed from a portion of the township on February 11, 1813. The township is closely associated with that now much more widely known town and several localities within West Windsor use Princeton in their name, the most notable of those being Princeton Junction. The USPS 'Princeton' post office (08540) facility is located within West Windsor, and covers parts of the township designated by Princeton, NJ mailing addresses.A portion of Princeton University, covering 400 acres (160 ha) south of Lake Carnegie, is located in West Windsor. The University agreed in 2009 to make an annual payment in lieu of taxes of $50,000 that would be indexed to inflation to cover 81 acres (33 ha) of land in the township that the university had purchased in 2002.West Windsor is frequently ranked among the highest-income municipalities in New Jersey. In 2008, Forbes listed West Windsor as the 15th most affluent neighborhood in the U.S. Using 2012–2016 data from the U.S. Census Bureau, NJ.com listed the township as the 9th highest-income in the state in its January 2018 article "The 19 wealthiest towns in New Jersey, ranked." Based on data from the American Community Survey for 2013–2017, West Windsor residents had a median household income of $175,684, ranked 4th in the state among municipalities with more than 10,000 residents, more than double the statewide median of $76,475.