Oak Grove is a home rule-class city adjacent to the Fort Campbell army base in Christian County, Kentucky, in the United States. The population was 7,489 as of the 2010 U.S. Census. It is part of the Clarksville, Tennessee metropolitan area.
The first post office in Oak Grove was established in 1828. The community was named for oak trees near the original town site. The Clarksville Railroad was extended to Oak Grove in the 19th century.
With construction of nearby Fort Campbell in the Second World War, Oak Grove's population grew. The city was incorporated by the state legislature on September 24, 1974.
Oak Grove is located in southeastern Christian County at 36°39′30″N 87°25′10″W (36.658374, -87.419565). Its southern border is the Tennessee state line, and it is bordered to the west by Fort Campbell. Hopkinsville, the Christian County seat, touches the northwest corner of Oak Grove along Fort Campbell Boulevard (U.S. Route 41 Alternate). Interstate 24 forms the northeast boundary of Oak Grove, with access from exit 86 (US 41 Alt.) and exit 89 (Kentucky Route 115).