The Buffalo Commons is a conceptual proposal to create a vast nature preserve by returning 139,000 square miles (360,000 km2) of the drier portion of the Great Plains to native prairie, and by reintroducing the American bison ("buffalo"), that once grazed the shortgrass prairie. The proposal would affect ten states: Montana, Wyoming, Colorado, Oklahoma, New Mexico, Texas, North Dakota, South Dakota, Nebraska, and Kansas.[1]