Grand Prismatic Spring is the largest hot spring in the United States, and one of the largest in the world. The feature is located in Midway Geyser Basin—so named because it is between the Upper and Lower Geyser Basins—and is one of the most popular attractions in Yellowstone National Park.

The West, South and East entrances and nearly all roads in Yellowstone National Park will be closed to regular vehicle traffic November 1.

Some lodging prices in Yellowstone National Park are effectively blocking a wide segment of Americans, whose tax dollars help pay for the National Park System out of experiencing a night or two in the park's iconic lodges.

Yellowstone is covered with evidence of glaciers. About 22,000 to 14,000 years ago, during the most recent ice age, ice draped the region to a thickness of a kilometer—that’s over half a mile! When the ice melted, it left debris everywhere, mantling much of the surface of Yellowstone National Park. For example, Hayden Valley, located between Yellowstone Lake and the Grand Canyon of the Yellowstone, contains glacial and lake sediment associated with multiple ice ages.