Mount Holly is a township in Burlington County, New Jersey, United States. It is the county seat of Burlington County and an eastern suburb of Philadelphia. As of the 2010 United States Census, the township's population was 9,536, reflecting a decline of 1,192 (−11.1%) from the 10,728 counted in the 2000 Census, which had in turn increased by 89 (+0.8%) from the 10,639 counted in the 1990 Census. Mount Holly gives its name to the National Weather Service Weather Forecast Office for the Philadelphia metropolitan area, though the office is actually located in adjacent Westampton.
What is now Mount Holly was originally formed as Northampton on November 6, 1688. Northampton was incorporated as one of New Jersey's initial group of 104 townships created by an act of the New Jersey Legislature on February 21, 1798. Portions of the township were taken to form Little Egg Harbor Township (February 13, 1740, now part of Ocean County), Washington Township (November 19, 1802), Pemberton borough (December 15, 1826), Coaxen Township (March 10, 1845, now known as Southampton Township), Pemberton Township (March 10, 1846), Westampton Township (March 6, 1850) and Lumberton Township (March 14, 1860). The township was renamed Mount Holly as of November 6, 1931, based on the results of a referendum held three days earlier. The township was named for hills covered with holly trees. Some areas of today's Mount Holly were known as Bridgetown.
The first European settlement in what is now Mount Holly began in 1677, when Walter Reeves acquired land from the Lenape (Delaware) Native Americans living in the area. He constructed a dam on Rancocas Creek to channel water through a raceway to power a grist mill and saw mill.