South Hamilton is a postal address assigned to ZIP code 01982 by the Postal Service and is part of the town of Hamilton, Essex County, Massachusetts, United States. The designation arose in the 1960s when the Postal Service built a new modern post office in downtown Hamilton with the intention of closing the original post office 2 miles north on the same road. Due to public objection, the original post office was preserved and remains open to this day. To distinguish between the two post offices in an era when the use of ZIP code was not yet mandatory, the new post office was designated the "South Hamilton" post office.