You’ll Ace This United States Geography Quiz If You’ve Visited All 50 States

The longest known cave system in the world is in the United States and is called…

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Frozen Niagara limestone formation, 75 foot high, 50 foot wide and 10 foot thick at Mammoth Cave National Park, Kentucky.
Retry Correct Incorrect Mammoth Cave is the longest cave system not only in the United States but in the entire world. Located in Kentucky, Mammoth Cave stretches more than a whopping 420 miles.
Jeffrey Greenberg/Universal Images Group via Getty Images
Jeffrey Greenberg/Universal Images Group via Getty Images

The longest known cave system in the world is in the United States and is called…

  • Luray Caverns
  • Wind Cave
  • Mammoth Cave
  • Meramec Caverns
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