It is called the Devils Tower because a guys interpreter misinterpreted it to be Bad God's Tower. Theodore Roosevelt later changed it to be Devils Tower.
This is a silly question but it's because a devil is a bad god and they own it
Devil's Tower is located in the Black Hills near Hulett and Sundance In Crook County, northeastern Wyoming above The Belle Fourche River.
crook county
Devil's Tower is 105 years old since president Theodore Rosevelt declared it a National Monument.