"Black Saturday" of the Yellowstone fire in Yellowstone National Park

The Yellowstone fires of 1988 collectively formed the largest wildfire in the recorded history of Yellowstone National Park in the United States. Starting as many smaller individual fires, the flames quickly spread out of control due to drought conditions and increasing winds, combining into several large conflagrations which burned for several months. The fires almost destroyed two major visitor destinations and, on September 8, 1988, the entire park was closed to all non-emergency personnel for the first time in its history. Only the arrival of cool and moist weather in the late autumn brought the fires to an end. A total of 793,880 acres (3,213 km²), or 36 percent of the park, burned at varying levels of severity.

Yellowstone National Park is a national park of the United States located in the northwest corner of the state of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U.S. Congress through the Yellowstone National Park Protection Act and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone was the first national park in the US, and is also widely understood to be the first national park in the world. 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, the subalpine forest is the most abundant. It is part of the South Central Rockies forests ecoregion.