Linden is a city in southeastern Union County, in the U.S. state of New Jersey. It is part of the New York metropolitan area, located about 13 miles (21 km) southwest of Manhattan and bordering Staten Island, a borough of New York City, across the Arthur Kill. As of the 2020 United States census, the city's population was 43,738, an increase of 3,239 (+8.0%) from the 2010 census count of 40,499, which in turn reflected an increase of 1,105 (+2.8%) from the 39,394 counted in the 2000 census. In 2015, Linden was listed as the most polluted community in New Jersey, based on the volume of toxic chemicals released into the local environment by facilities in the city.