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. As of the 2010 Census, the county's population was 66,083, 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.
European settlement began with English colonists in the seventeenth century, who were settling both sides of the Delaware River. They established a colonial court in the area in 1681, but Salem County was first formally organized within West Jersey on May 17, 1694, from the Salem Tenth. Pittsgrove Township was transferred to Cumberland County in April 1867, but was restored to Salem County in February 1868. The area was initially settled by Quakers.