Mammoth Cave National Park is an American national park in west-central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world.

Since the 1972 unification of Mammoth Cave with the even-longer system under Flint Ridge to the north, the official name of the system has been the MammothFlint Ridge Cave System. The park was established as a national park on July 1, 1941, a World Heritage Site on October 27, 1981, an international Biosphere Reserve on September 26, 1990 and an International Dark Sky Park on October 28, 2021.

The park's 52,830 acres (21,380 ha) are located primarily in Edmonson County, with small areas extending eastward into Hart and Barren counties. The Green River runs through the park, with a tributary called the Nolin River feeding into the Green just inside the park. Mammoth Cave is the world's longest known cave system with more than 420 miles (680 km) of surveyed passageways, which is nearly twice as long as the second-longest cave system, Mexico's Sac Actun underwater cave.

Kentucky (US: (listen) kən-TUK-ee, UK: ken-), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States, 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 Commonwealth's northern border is defined by the Ohio River. Its capital is Frankfort, and its two largest cities are Louisville and Lexington. The state's population in 2020 was approximately 4.5 million.

Kentucky was admitted into the Union as the 15th state on June 1, 1792, splitting from Virginia in the process. It is known as the "Bluegrass State", a nickname based on Kentucky bluegrass, a species of grass found in many of its pastures, which has supported the thoroughbred horse industry in the center of the state. Historically, it was known for excellent farming conditions for this reason. Kentucky ranks 5th nationally in goat farming, 8th in beef cattle production, and 14th in corn production. Kentucky has also been a long-standing major center of the tobacco industry. Today, Kentucky's economy has expanded to importance in non-agricultural sectors, including auto manufacturing, energy fuel production, and medical facilities. The state ranks 4th among U.S. states in the number of automobiles and trucks assembled.The state is home to the world's longest cave system in Mammoth Cave National Park, as well as the greatest length of navigable waterways and streams in the contiguous United States and the two largest man-made lakes east of the Mississippi River. Kentucky is also known for its unique blended culture, which includes horse racing, bourbon, moonshine, coal, "My Old Kentucky Home" historic state park, automobile manufacturing, tobacco, bluegrass music, college basketball, Louisville Slugger baseball bats, Kentucky Fried Chicken, and the Kentucky colonel.