"They lived and moved as no other quadrupeds ever have, in great multitudes, like grand armies in review, covering scores of square miles at once...They were so numerous they frequently stopped boats in the rivers, threatened to overwhelm travelers on the plains, and in later years derailed locomotives and cars, until railway engineers learned by experience the wisdom of stopping their trains whenever there were buffaloes crossing the track." — William T. Hornady, head of the National Zoological Park

Related Content The Historic Return of the American Bison

By 1889, when William T. Hornady headed the Natioanl Zoo, there were just 1,091 buffalo left.

Over time, and with serious conservation efforts, some bison populations have been able to recover. The biggest, says Defenders of Wildlife, is in Yellowstone National Park, where 4,000 wild plains bison still roam. And yesterday the federal government proposed a tentative plan to reintroduce some of these Yellowstone buffalo to the world outside the park's borders, says Reuters, on public land in "states such as Colorado, Arizona, New Mexico, Nebraska and South Dakota."

Surprisingly, there has been some strong opposition to the plan to bring back this iconic American mammal, says Reuters. Bison can carry diseases that affect cattle, and ranchers are worried about the risk wild herds of bison may pose. Ranchers are also worried the wild bison may graze on the federal lands they use to feed their cattle.

For anyone with an opinion either for or against the plan, the department will be seeking public comment until September.