The North American Bison formerly numbered in the millions and thrived on Colorado’s Great Plains for millennia until overhunting and other environmental stresses drove them to extinction in the nineteenth century. Several bison herds now roam Colorado, thanks to reintroduction efforts in the twentieth century, and ranchers even rear them for meat.

The County of Denver maintains a bison herd in Genesee Park, Colorado, approximately twenty miles west of the city. The bison are direct descendants of the last herd of bison in the wild in the United States. In 1914, a herd of seven bison was transported from Yellowstone National Park.