Yellowstone National Park

Interesting facts

Two-thirds of all the world's geysers are in Yellowstone, and at least 1,283 have erupted there, with around 465 active in a typical year.

About 96 per cent of the park lies in Wyoming, three per cent in Montana and one per cent in Idaho.

The Yellowstone Caldera measures about 72 by 45 km and was created by an eruption 640,000 years ago that released more than 1,000 cubic km of material.

The largest known eruption of the hotspot, 2.1 million years ago, ejected about 2,450 cubic kilometres of material.

The ground is restless: Yellowstone records 1,000 to 3,000 small earthquakes a year.

Yellowstone Lake covers about 352 square kilometres, the largest high-elevation lake in North America, with some 180 km of shoreline.

The Lower Falls of the Yellowstone River, the park's highest waterfall, drop 94 metres.

The Washburn Expedition of 1870 named Old Faithful after noticing that it erupted regularly, about every 90 minutes.

For 30 years, from 1886, the US Army managed the park.

The great fires of 1988 burned more than a third of the park.

Why it is worth it

On 1 March 1872, Ulysses S. Grant signed a piece of legislation that had no real precedent anywhere in the world: setting aside more than two million acres of Wyoming and Montana territory not for a king, a church, or a private estate, but simply to be left alone. Yellowstone wasn't just America's first national park — it was the first national park, period, the model every other country's park system has copied since.

That it needed protecting at all says something about what's underneath it. Yellowstone sits on top of one of the largest active volcanic systems on Earth, and the geothermal features scattered across the park — geysers, hot springs, mudpots, fumaroles — aren't a curiosity on the side, they're most of the reason the place exists as a park in the first place: it holds well over half of all the geysers on the planet. Old Faithful gets the crowds, but the more revealing feature is Grand Prismatic Spring, whose rainbow rings of colour come from heat-loving bacteria living in water too hot and too mineral-rich for almost anything else to survive in.

The park's more recent history is a case study in how fragile even a protected wilderness can be. Wolves were hunted to extinction inside Yellowstone by the 1920s, and their absence let elk populations balloon and strip valleys of young trees — a chain of consequences ecologists were still tracing decades later. When wolves were reintroduced in 1995, willow and aspen began recovering within a few years, an outcome now taught as one of the clearest real-world demonstrations of what a single missing predator can do to an entire landscape.

Best time to visit

Late spring through early autumn is when interior roads are fully open and wildlife is easiest to see, though snow can linger at higher elevations into May. Winter access is limited to guided snowcoach and snowmobile routes, but rewards visitors with steam-wrapped geyser basins and elk gathered at lower elevations.

Getting there

127 km from Bozeman. Yellowstone Airport (WYS) is about 50 km away.

From the encyclopaedia

Yellowstone National Park is a national park of the United States located mainly in the northwest corner of the state of Wyoming, with small portions extending into Montana and Idaho. The park is known for its wildlife and its many geothermal features, especially the Old Faithful geyser, one of its most popular. While it represents many types of biomes, subalpine forest is the most abundant. It is part of the South Central Rockies forests ecoregion.

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