List of longest caves in the United States

The following is a list of the longest caves in the United States per length (over 50 kilometres or 30 miles) of documented passageways.

Many passageways are still being discovered; this list is based on the latest verifiable data.

[1] Some caves and cave systems are partially accessible to the general public.

Other caves have restricted access; restrictions may include limiting access to experienced spelunkers or scientific research teams.

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Mammoth Cave , the longest known cave system in the world