Montana officials filed a lawsuit on Dec. 31 in U.S. District court alleging that the DOI and NPS have failed to keep bison populations in check at Yellowstone National Park. NPS officials say the park can support a larger herd,

Bison in Yellowstone National Park may seem calm, but approaching them is extremely dangerous. Learn why these massive animals should always be admired from a safe distance and the steps to ensure your safety while visiting the park.

State officials say they're worried about bison passing on disease to cattle outside the park—but wildlife managers say it's never happened before.