Radcliff is a home rule-class city in Hardin County, Kentucky, in the United States. The population was 21,692 at the 2010 census, and in 2019 the estimated population was 22,914. It is included in the Elizabethtown–Fort Knox Metropolitan Area.
Its economy is largely dominated by the adjacent U.S. Army base Fort Knox and by the nearby city of Elizabethtown. Radcliff's population previously fluctuated greatly depending on the deployments of the units at the base, but the BRAC reorganization of 2005, and the quartering of the U.S. Army's Human Resources Command to Fort Knox has created a larger and more stable population.
Radcliff is in northern Hardin County at 37°49′48″N 85°56′44″W (37.829918, -85.945541). It is bordered to the north by Fort Knox and to the west by Vine Grove. U.S. Route 31W runs through the east side of the city, leading north 34 miles (55 km) to Louisville and south 11 miles (18 km) to Elizabethtown.
According to the United States Census Bureau, Radcliff has a total area of 12.4 square miles (32.2 km2), of which 12.4 square miles (32.1 km2) are land and 0.04 square miles (0.1 km2), or 0.25%, are water.
The former unincorporated community of Rogersville, named for a local family, is in the southern part of Radcliff along US 31W and Kentucky Route 447.
Incorporated in 1956, Radcliff was first settled in 1919, when Horace McCullum subdivided lots along Wilson Avenue and sold them at auction to the highest bidder. McCullum named the new community after Major William Radcliffe, head of the Quartermaster Corps at the newly established Camp Henry Knox. After selling the general store he had opened in the new town, McCullum no longer played a role in its development.