Locust Grove is a city in Henry County, Georgia, United States. The population was 2,322 at the 2000 census. Census estimates for 2005 show a population of 3,434. Some unincorporated communities such as Luella and many rural areas surround Locust Grove and addresses in those communities have Locust Grove postal addresses. The City of Locust Grove derived its name from a grove of locust trees that could be seen throughout the town.