Union is a township in Union County, New Jersey, United States. In the 18th century, the area that is now Union was then called Connecticut Farms. As of the 2010 United States Census, the township population was 56,642, the highest recorded in any decennial census, reflecting an increase of 2,237 (+4.1%) from the 54,405 counted in the 2000 Census, which had in turn increased by 4,381 (+8.8%) from the 50,024 counted in the 1990 Census.