Theodore Roosevelt went West to the Dakotas (Present day North Dakota, near Medora) to overcome the great personal loss of both his mother and wife on the same day in New York. During his time in the West, before a blizzard killed his cattle and sent him back East, TR gained an understanding about how the American Bison had been decimated by overhunting. He never forgot that.
Pioneering conservationists TR and William Hornaday originally founded the American Bison Society (ABS) at the Bronx Zoo in 1905 to save the bison from extinction. In 1907, Bronx Zoo staff sent 15 bison by train to Oklahoma’s Wichita Mountains Wildlife Preserve to help restore the western Plains’ depleted bison population.
The World Conservation Society has taken up the mantle of the American Bison Society. Their site can be viewed here.