Stack Island was also associated with river pirates and counterfeiters in the late 1790s. In 1809, the last major river pirate activity took place, on the Upper Mississippi River, and river piracy in this area came to an abrupt end, when a group of flatboatmen raided the island, wiping out the river pirates. From 1790 to 1834, Cave-In-Rock was the principal outlaw lair and headquarters of river pirate activity in the Ohio River region, from which Samuel Mason led a gang of river pirates on the Ohio River.