Neptune City is a borough in Monmouth County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 4,869, reflecting a decline of 349 (-6.7%) from the 5,218 counted in the 2000 Census, which had in turn increased by 221 (+4.4%) from the 4,997 counted in the 1990 Census.
The Borough of Neptune City was incorporated on October 4, 1881, based on a referendum held on March 19, 1881. The boundaries included all of present-day Neptune City, along with what is now Avon-by-the-Sea and the southern portion of Bradley Beach. On March 23, 1900, a bill approved in the New Jersey Legislature created the Borough of Avon-by-the-Sea. On March 13, 1907, the eastern portion of Neptune City was annexed to the Borough of Bradley Beach.
The earliest borough hall was erected in 1902 at the northwest corner of Evergreen Avenue and Railroad Avenue (now Memorial Drive).