Salem County is the westernmost county in the U.S. state of New Jersey. Its western boundary is formed by the Delaware River and its eastern terminus is the Delaware Memorial Bridge, which connects the county with New Castle, Delaware. Its county seat is Salem. The county is part of the South Jersey region of the state.

Salem is a city in Salem County, in the U.S. state of New Jersey. It is the county seat of Salem County, the state's most rural county. The name Salem, for both the city and county, is derived from the Hebrew word shalom, meaning peace. As of the 2020 United States census, the city's population was 5,296, an increase of 150 (+2.9%) from the 2010 census count of 5,146, which in turn reflected a decrease of 711 (−12.1%) from the 5,857 counted in the 2000 census. Salem is part of the Delaware Valley or Philadelphia greater metropolitan area.