In Kentucky's Mammoth Cave National Park, a Cave Research Foundation exploration and mapping team discovers a link between the Mammoth and Flint Ridge cave systems, making it the longest known cave passageway in the world.

Kentucky, officially the Commonwealth of Kentucky, is a landlocked state in the Southeastern region of the United States. It borders Illinois, Indiana, and Ohio to the north, West Virginia to the northeast, Virginia to the east, Tennessee to the south, and Missouri to the west. Its northern border is defined by the Ohio River. Its capital is Frankfort and its most populous city is Louisville. As of 2024, the state's population was approximately 4.6 million.

Mammoth Cave National Park is a national park of the United States in south-central Kentucky. It encompasses portions of Mammoth Cave, the longest known cave system in the world. The park's 52,007 acres (21,046 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.