Pine Mountain is a town in Harris and Meriwether counties in the U.S. state of Georgia. As of the 2020 census it had a population of 1,216. …Pine Mountain is a town in Harris and Meriwether counties in the U.S. state of Georgia. As of the 2020 census it had a population of 1,216. The Harris County portion of Pine Mountain is part of the Columbus, GA-AL metropolitan statistical area, while the small portion that extends into Meriwether County is part of the Atlanta-Sandy Springs-Roswell metropolitan statistical area.