The Clark Thread Company Historic District, located at 900 Passaic Avenue, East Newark, Hudson County, New Jersey, United States, is a large mill complex.

[4] The former Clark Thread Company facilities lie overlooking the Passaic River in East Newark, covering an area of about 13 acres (5.3 ha) bounded by Passaic, Grant, and Central Avenues, and a railroad right-of-way that parallels Johnston Avenue.

It was the largest threadmaker in the nation by 1873, and doubled in size by William Clark's death in 1897, when it merged with competitor J&P Coats.

Coats and its successors continued to operate on this site until the 1930s, when they began moving production to the American South.

In 1888, Scientific American recognized Clark Thread Works to have the highest chimney in the United States at 335 ft.[5]