Route 159 is a short, 1.36-mile (2.19 km) highway in the Montville and Fairfield areas. Route 159's western and eastern termini are both at U.S. Route 46 (US 46). Route 159 is called locally as Bloomfield Avenue, Oak Road, and Clinton Road during its length.

Fairfield is a township in far northwestern Essex County, in the U.S. state of New Jersey. As of the 2020 United States census, the township's population was 7,872, an increase of 406 (+5.4%) from the 2010 census count of 7,466, which in turn reflected an increase of 403 (+5.7%) from the 7,063 counted in the 2000 census. Fairfield was the least densely populated town in Essex County in 2020.