Mountain Grove is a city in Texas and Wright Counties in the U.S. state of Missouri, located in south central Missouri. The population was 4,789 at the 2010 census. A post office called Mountain Grove has been in operation since 1875. The community owes its present name to a stand of trees near the original elevated town site.In 1841 a settlement was built on land east of Mountain Grove near a spring in a grove of hickory timber. A post office was established in Hickory Spring in 1853. The post office, in 1878, was named for Judge Robert W. Fyan, a prominent figure in early county history. In 1859, a general store was built at the crossroads about a mile west of Hickory Spring. The old post office established under the name of Fyan before the Civil War changed to Mountain Grove, with reference to its location on a ridge in a grove of trees, in 1878.This became known as the "mountain store, mountain grove or the mountain" because the elevation is 1,525 feet.