Salem is a city in Salem County, New Jersey, United States. As of the 2010 United States Census, the city's population was 5,146, reflecting a decrease of 711 (-12.1%) from the 5,857 counted in the 2000 Census, which had in turn declined by 1,026 (-14.9%) from the 6,883 counted in the 1990 Census, an overall drop of more than 25% over the two decades. It is the county seat of Salem County, the state's most rural county.