Myrtle is an unincorporated community in Mingo County, West Virginia, United States. Myrtle is located on U.S. Route 119 and the Trace Fork, 8 miles northeast of Williamson. Myrtle had a post office, which opened on September 2, 1891, and close…Myrtle is an unincorporated community in Mingo County, West Virginia, United States. Myrtle is located on U.S. Route 119 and the Trace Fork, 8 miles northeast of Williamson. Myrtle had a post office, which opened on September 2, 1891, and closed on August 22, 1992.