Route 57 is a state highway located in Warren County in the U.S. state of New Jersey. It runs 21.10 mi (33.96 km) from an interchange with U.S. Route 22 (US 22) in Lopatcong Township to an intersection with Route 182 and County Route 517 (CR 517) in Hackettstown. The route passes through mostly rural areas of farmland and mountains in Warren County. It also passes through Washington, where Route 57 crosses Route 31. The route is designated a scenic byway, the Warren Heritage Scenic Byway, by the state of New Jersey due to the physical environments it passes through as well as from historical sites along the way such as the Morris Canal.

Warren County is a county located in the U.S. state of New Jersey. According to the 2020 census, the county was the state's 19th-most populous county, with a population of 109,632, its highest decennial count ever and an increase of 940 (+0.9%) from the 2010 census count of 108,692, which in turn reflected an increase of 6,255 (+6.1%) from 102,437 counted at the 2000 census. The county is part of the North Jersey region of the state.