The Washburn Expedition of 1870 explored the region of northwestern Wyoming that two years later became Yellowstone National Park. Led by Henry D. Washburn and Nathaniel P. Langford, and with a U.S. Army escort headed by Lt. Gustavus C. Doane, the expedition followed the general course of the Cook–Folsom–Peterson Expedition made the previous year.
During their explorations, members of the party made detailed maps and observations of the Yellowstone region, exploring numerous lakes, climbing several mountains, and observing wildlife. The expedition visited both the Upper and Lower Geyser Basins, and after observing the regularity of eruptions of one geyser, decided to name it Old Faithful, since it erupted about once every 74 minutes.
