Yellowstone - America's first national park was established in 1872. The park is mostly located in the U.S. state of Wyoming, although it also reaches into Montana and Idaho.

Yellowstone National Park spans an area of 3,472 square miles (8,987 km²), with extraordinary geysers, hot springs, lakes, canyons, rivers and mountain ranges. Yellowstone Lake is one of the largest high-altitude lakes in North America and is centered over the Yellowstone Caldera, the largest supervolcano on the continent. The caldera is considered an active volcano; it has erupted with tremendous force several times in the last two million years.

Yellowstone National Park has one of the world's largest petrified forests, trees which were long ago buried by ash and soil and transformed from wood to mineral materials. There are 290 waterfalls of at least 15 feet (4.5 m) in the park, the highest being the Lower Falls of the Yellowstone River at 308 feet (94 m).

Old Faithful (picture on right) is the most popular geyser in the world erupting approximately every 91 minutes.