On August 20, the single worst day of the Yellowstone fires of 1988 and later named Black Saturday, more than 150,000 acres (610 km²) were consumed during one of many intense fires.

The Yellowstone fires of 1988 together formed the largest wildfire in the recorded history of Yellowstone National Park in the United States.

On that single day, more land burned than in all other fires combined since the establishment of the park.

The fires almost destroyed two major visitor destinations and, on September 8, the Yellowstone National Park was closed to all non-emergency personnel for the first time in its history.

Old Faithful is a cone geyser located in the park with more than 1,000,000 eruptions recorded, every 44 to 125 minutes shooting 14,000 to 32,000 L of boiling water to a height of 32 to 56 m lasting from  1 ¹⁄₂ to 5 minutes.