 From approximately 1797 until 1799, the cave was a hideout for a notorious gang of bandits headed by Samuel Mason, who preyed upon the lawless river commerce.The outlaws Frank and Jesse James of the notorious James–Younger Gang also hid out in the cave, according to local lore, leaving their marks in the cave.Later in the 19th century, Cave-in-Rock was tamed by settlers who formed the river town of Cave-In-Rock, Illinois near the cave.