Locust Grove is a town in Mayes County, Oklahoma, United States. The population was 1,423 at the 2010 census, a 4.2 percent increase over the figure of 1,366 recorded in 2000.
Locust Grove was the site of the Battle of Locust Grove, a small Civil War engagement on July 3, 1862, in which approximately 250 Union troops surprised and destroyed a similar-sized Confederate contingent, killing about 100 and capturing another 100 while sustaining only minimal losses. The escaping Confederates retreated toward Tahlequah, leading to a loss of morale and desertions among the Cherokee Confederate supporters.
A small community, named for the grove of locust trees where this battle took place, formed here, in the Cherokee Nation of Indian Territory. A post office was established here on March 26, 1873. Jim Bryan moved the post office to his store in 1908, after Oklahoma became a state and Mayes County was established. In 1910, Louie Ross bought the Bryan store and moved it to his father's ranch house. The community of Locust Grove soon relocated closer to the store, and soon had a cemetery, a gristmill, two blacksmith shops, and a separate building to house the post office.
The existing townsite was established in 1912 by O.W. Killam, a lawyer, merchant, realtor and promoter who bought the Cherokee allotment that had belonged to Elzina Ross in connection with the construction of the Kansas, Oklahoma and Gulf Railway. Killam platted the townsite and incorporated it March 4, 1913
The town has had its share of tragedy. In June 1952, the county attorney Jack Burris was assassinated at his home at Locust Grove in one of the most famous unsolved murders in Oklahoma history. In 1977 it was the location of the Oklahoma Girl Scout murders, in which three young girls were raped and murdered as they were camping at the nearby Camp Scott Girl Scout facility.