Dayton is an unincorporated community and census-designated place in South Brunswick Township, Middlesex County, New Jersey, in the United States. At the 2020 United States census, the CDP's population was 8,138, up from 7,063 in 2010. Dayton has a post office with its own ZIP Code that encompasses the entire CDP, as well as some surrounding areas. The community was named for William L. Dayton, a local attorney who later served in the United States Senate, or for Jonathan Dayton, the youngest person to sign the United States Constitution, who later served as a U.S. senator from New Jersey.