In the 19th century, Kentucky's Mammoth Cave launched an entire, very competitive cave tourism industry in the area, In 1925, Floyd Collins was trapped in the cave system, which was the beginning of the end of the cave wars.
Research:

SYMHC Classics: Swill Milk
39:22

Behind the Scenes Minis: Mary, Beulah, Baby Alive
33:26

Beulah Louise Henry
39:37