Clark is a township in southern Union County, New Jersey, United States. As of the 2010 United States Census, the township's population was 14,756 reflecting an increase of 159 (+1.1%) from the 14,597 counted in the 2000 Census, which had in turn declined by 32 (-0.2%) from the 14,629 counted in the 1990 Census.
The territory that would become Clark was originally a part of several early villages. The Robinson Plantation House and The Squire Hartshorne House, buildings from the late 17th century, are remnants of the era. The Homestead Farm at Oak Ridge was the site of a skirmish preceding the Battle of Short Hills. In 1858, after the City of Rahway was incorporated, the area of present-day Clark was designated as the 5th Ward of Rahway. Clark was incorporated as a township by an act of the New Jersey Legislature on March 23, 1864, from portions of Rahway. The township was named for Abraham Clark, a signer of the Declaration of Independence. Portions of the township were taken to form Cranford Township (March 14, 1871) and Winfield Township (August 6, 1941).
New Jersey Monthly magazine ranked Clark as its 33rd best place to live in its 2008 rankings of the "Best Places To Live" in New Jersey. In 2013, New Jersey Monthly magazine ranked Clark 174th in its rankings of "Best Places To Live" in New Jersey.
According to the United States Census Bureau, the township had a total area of 4.45 square miles (11.53 km2), including 4.27 square miles (11.07 km2) of land and 0.18 square miles (0.47 km2) of water (4.04%).
Unincorporated communities, localities and place names located partially or completely within the township include Ashbrook, Florence Mills, Lenox, Madison Hill and Picton.
The Rahway River Parkway along the Rahway River runs through the township.
The town borders Scotch Plains and Westfield on the west, Cranford and Winfield Park on the north, Linden and Rahway on the east, and Edison and Woodbridge Township in Middlesex County on the south.
The 2010 United States Census counted 14,756 people, 5,562 households, and 4,038 families in the township.