Devils Postpile National Monument is located near Mammoth Mountain in extreme northeastern Madera County in eastern California. It was created in 1911, and protects Devils Postpile, an unusual formation of columnar basalt.
Devils Postpile National Monument encompasses 798 acres (323 ha) and includes two main tourist attractions: Devils Postpile (a columnar basalt formation); and Rainbow Falls, a waterfall on the Middle Fork of the San Joaquin River. In addition, the John Muir Trail and Pacific Crest Trail merge into one trail as they pass through the monument.
The Monument was once part of Yosemite National Park, but discovery of gold in 1905 near Mammoth Lakes prompted a boundary change that left the Postpile on adjacent public land.Later, a proposal to build a hydroelectric dam called for blasting the Postpile into the river. Influential Californians, including Walter L. Huber, persuaded the federal government to stop the demolition and in 1911, President William Howard Taft protected the area as a National Monument.