In 1941.
On 1 July 1941.
Mammoth Cave National Park was established as a national park on 1 July 1941.
Mammoth Cave National Park was established as a national park on 1 July 1941.
On 1 July 1941.
On 1 July 1941.
On 1 July 1941.
Mammoth Cave National Park was established as a national park on 1 July 1941.
In 1941.
Yes since 1941.
Mammoth Cave was established as a national park on July 1st, 1941.
On 1 July 1941.
On 1 July 1941.
On 1 July 1941.