Chatham is an unincorporated community in Licking County, in the U.S. state of Ohio.[1] Chatham was originally called Harrisburgh, and under the latter name was laid out in 1829.[2] A post office was established under the name Chatham in 1836, and remained in operation until 1894.This Licking County, Ohio state location article is a stub.You can help Wikipedia by expanding it.