Mercer County, New Jersey was established on February 22, 1838 and named after Continental Army General, Hugh Mercer, who died in the Battle of Princeton! Its county seat is Trenton, and its fair is held in Hopewell Township! You might recognize the New Jersey state capitol, Princeton University, the site where George Washington landed after crossing the Delaware, and the site where the Martians landed in George Orwell’s famous radio broadcast of The War of the Worlds, which are located in this county!