Old Faithful

Old Faithful currently erupts approximately every 60 to 110 minutes, with intervals varying based on the duration and intensity of the previous eruption. Each eruption lasts roughly 1.5 to 5 minutes, and intervals have generally lengthened over the decades due to changes in the geyser's underground plumbing.

During a typical eruption, the water column reaches heights of 106 to 185 feet (approximately 32 to 56 meters). Shorter-duration eruptions tend to produce taller columns, while longer eruptions release more water at lower peak heights.

Old Faithful is located in the Upper Geyser Basin of Yellowstone National Park, primarily in Wyoming. The Upper Geyser Basin contains approximately 150 geysers within one square mile, making it one of the most concentrated geyser fields in the world, though Old Faithful is by far the most visited feature.

Old Faithful was named by members of the Washburn-Langford-Doane Expedition in 1870, who observed its predictable eruption pattern during their exploration of the Yellowstone region. Their reports, along with the earlier Hayden Survey of 1871, contributed directly to Congress establishing Yellowstone as the first U.S. national park in 1872.