• A bull elk bugles in Yellowstone National Park


    National Park ID,MT,WY

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  • Craig Pass Closed for the Season; Mammoth to Norris, Expect 30-minute Delays

    The road linking West Thumb and Old Faithful is closed for the season—traffic should detour through West Thumb, Lake, and Canyon. More »

Environmental Factors

View from Calcite Springs Overlook
View from Calcite Springs Overlook

Yellowstone National Park forms the core of the Greater Yellowstone Ecosystem. At 28,000 square miles, it is one of the largest, nearly intact temperate-zone ecosystems on Earth.

Many environmental factors affect the health of this dynamic ecosystem. Ecological and geological processes continue to shape the environment as they have for millennia. Human-caused factors also have an influence. Air pollution, climate change, and the introduction of nonnative species have had an impact on natural resources worldwide. Yellowstone provides a place where scientists can study how these trends affect ecosystems, and foster an understanding of what changes we should expect in the future.

Did You Know?

Summer Crowd at Old Faithful.

At peak summer levels, 3,500 employees work for Yellowstone National Park concessioners and about 800 work for the National Park Service.