Lawrence County is located in the southwest portion of the U.S. state of Missouri, in the area of the Ozarks. As of the 2020 census, the population was 38,001. Its county seat is Mount Vernon. The county was organized in 1845 and named for James Lawrence, a naval officer from the War of 1812 known for his battle cry, "Don't give up the ship!"

Mount Vernon is a city in and the county seat of Lawrence County, Missouri, United States. The population was 4,575 as of the 2010 census. It was estimated to be 4,960 by the City of Mount Vernon on July 1, 2020.