Kentucky, constituent state of the United States of America. It is bordered by Illinois, Indiana, and Ohio to the north; West Virginia and Virginia to the east; Tennessee to the south; and Missouri to the west. The capital, Frankfort, lies between the state’s two major cities Louisville and Lexington.
Mammoth Cave National Park, national park containing an extensive system of limestone caverns in west-central Kentucky, U.S. It was designated a World Heritage site in 1981. The park, authorized in 1926 but fully established only on July 1, 1941, occupies a surface area of 83 square miles (215