On what date was Mammoth Cave National Park established?

Mammoth Cave National Park was established on July 1, 1941.

The park protects Mammoth Cave in south-central Kentucky, part of the Mammoth–Flint Ridge Cave System, the longest known cave system in the world. Its creation followed years of land acquisition and often-contentious eminent-domain proceedings involving hundreds of parcels.

The date is sometimes confused with October 27, 1981, when Mammoth Cave National Park became a UNESCO World Heritage Site. Other milestones came later: it became an International Biosphere Reserve in 1990 and an International Dark Sky Park in 2021.

The cave itself was already famous long before national-park status. It was used by Indigenous peoples thousands of years ago, became a tourist attraction in the 19th century, and was mined for nitrate during the War of 1812. The national park designation brought the cave and its surrounding forests, rivers, and karst landscape under federal protection.