Old Faithful

The geyser whose reliable eruptions helped convince a skeptical Congress that Yellowstone's wonders were real, kickstarting the entire American national park idea.

Members of the 1870 Washburn-Langford-Doane Expedition, exploring the region that would become Yellowstone, named the geyser 'Old Faithful' for the unusual regularity of its eruptions compared to the area's many other, less predictable thermal features. Their published accounts of geysers, hot springs, and canyons in the region helped persuade a skeptical Congress and public that the reports weren't exaggeration.

In 1872, partly on the strength of accounts of features like Old Faithful, Congress established Yellowstone as the first National Park in the United States, and arguably the world, setting aside the region's geothermal wonders for public enjoyment rather than private development. Old Faithful itself erupts roughly every 44 to 125 minutes, sending water and steam 106 to 185 feet into the air for one and a half to five minutes at a time.

As tourism to the young park grew, the Northern Pacific Railroad and its partners built the Old Faithful Inn beside the geyser between 1903 and 1904. Designed by architect Robert Reamer, the massive log-and-stone building remains one of the largest log structures in the world. Today, park geologists can predict Old Faithful's next eruption within about a ten-minute window by tracking the duration of the previous one, letting visitors plan their viewing with rare confidence for a natural phenomenon.