Which state is home to Mammoth Cave, the world’s longest known cave system?

Mammoth Cave National Park in central Kentucky contains more than 420 miles of surveyed passageways, and explorers keep finding more. No other known cave system comes close.

In 1838, Stephen Bishop, an enslaved teenager who worked as a guide, began exploring and mapping the cave. He discovered many of its passages and crossed its underground rivers, and his map was used for decades.

During the War of 1812, miners dug saltpeter from the cave to make gunpowder. It became a national park in 1941.