Old Faithful is a cone geyser located in Yellowstone National Park in Wyoming, United States. Old Faithful was named in 1870 during the Washburn-Langford-Doane Expedition and was the first geyser in the park to receive a name. It is one of the most predictable geographical features on Earth, erupting every 35 to 120 minutes. The geyser, as well as the nearby Old Faithful Inn, is part of the Old Faithful Historic District.