Old Faithful is a cone geyser located in Yellowstone National Park in Wyoming. It was named in 1870 during the Washburn-Langford-Doane Expedition and was the first geyser in the park to receive a name. It is a highly predictable geothermal feature, and has erupted every 44 to 125 minutes since 2000. The geyser and the nearby Old Faithful Inn are part of the Old Faithful Historic District. Wikipedia