The Farmington River is a river, 46.7 miles (75.2 km) in length along its main stem, located in northwest Connecticut with major tributaries extending into southwest Massachusetts. The longest route of the river, from the origin of its West Branch, is 80.4 miles (129.4 km) long, making it the Connecticut River's longest tributary by 2.3 miles (3.7 km) over the major river directly to its north, the Westfield River. The Farmington River's watershed covers 609 square miles (1,580 km2). Historically, the river played an important role in small-scale manufacturing in towns along its course, but it is now mainly used for recreation and drinking water.