Salem County is a county located in the U.S. state of New Jersey. Its western boundary is formed by the Delaware River and it has the eastern terminus of the Delaware Memorial Bridge, connecting to New Castle, Delaware. Its county seat is Salem. The county is part of the Delaware Valley area. Salem County's Census-estimated population was 64,180 in 2015, representing a 2.9% decrease from the 66,083 enumerated at the 2010 Census, in turn increasing by 1,798 (+2.8%) from the 64,285 counted in the 2000 Census, retaining its position as the state's least populous county. The most populous place was Pennsville Township, with 13,409 residents at the time of the 2010 Census. Lower Alloways Creek Township covers 72.46 square miles (187.7 km2), the largest total area of any municipality.