Mount Sterling is an unincorporated community in western Gasconade County, Missouri, United States. Mount Sterling is located at the intersection of U.S. Route 50 and Missouri Route A. The Gasconade River flows past the west side of the town. The Gasconade-Osage county line is approximately one mile west of the community. The county seat of H…Mount Sterling is an unincorporated community in western Gasconade County, Missouri, United States. Mount Sterling is located at the intersection of U.S. Route 50 and Missouri Route A. The Gasconade River flows past the west side of the town. The Gasconade-Osage county line is approximately one mile west of the community. The county seat of Hermann is 18 miles to the northeast.