US 20 in Idaho: Craters of the Moon, Idaho Falls

To the left of the satellite photo the large basalt area of the Craters of the Moon National Park & Preserve are visible.

Idaho Falls is in the right of the photo.

After US Route 20 leaves Wyoming and the western end of Yellowstone National Park, it takes a southwestward trek through Idaho. The first major city that US Route 20 encounters after leaving Wyoming is Idaho Falls, Idaho. As US 20 approaches Idaho Falls from the north, it carries the names Rigby Highway. The City of Idaho Falls is the largest city in eastern Idaho, and the fourth largest city in the state. It serves as the county seat of Bonneville County. The city gets its name from the rapids and waterfalls on the Snake River.

According to Wikipedia:

“What became Idaho Falls was the site of Taylor’s Crossing, a timber frame bridge built across the Snake River. The bridge was built by Matt Taylor, a freighter, who, in 1865, built a toll bridge across a narrow black basaltic gorge of the river that succeeded a ferry nine miles upstream by a few years. Taylor’s bridge served the new tide of westward migration and travel in the region that followed the military suppression of Shoshone resistance at the Bear River Massacre near Preston, Idaho in 1863. The bridge improved travel for settlers moving north and west and for miners, freighters, and others seeking riches in the gold fields of central Idaho and western Montana. “


As US Route 20 turns west heading out of Idaho Falls, the name changes to West Broadway Street, and even father west, it becomes the West Arco Highway. As the road turns southwest of Arco, US20 runs concurrently with US 26 and US 93. Along this stretch of US20, and in the Snake River Plain, is the Craters of the Moon National Monument & Preserve.

This monument and preserve is one of the best preserved flood basalt areas in the continental United States. The landscape contains volcanic features including volcanic rifts, cinder cones, deep cracks, spatter cones, shield volcanoes and lava tubes.

The Monument was originally established on May 2, 1924, and in November 2000, the monument boundaries were expanded by President William J. Clinton by Presidential proclamation. It was officially designated as Craters of the Moon National Monument and Preserve in August 2002.

According to Wikipedia:

"The Monument and Preserve encompass three major lava fields and about 400 square miles (1,036 km2) of sagebrush steppe grasslands to cover a total area of 1,117 square miles (2,893 km2). All three lava fields lie along the Great Rift of Idaho, with some of the best examples of open rift cracks in the world, including the deepest known on Earth at 800 feet (240 m). There are excellent examples of almost every variety of basaltic lava as well as tree molds (cavities left by lava-incinerated trees), lava tubes (a type of cave), and many other volcanic features."


Further information on Idaho Falls and Craters of the Moon National Monument and Preserve can be found here:

The City of Idaho Falls
Wikipedia: Idaho Falls, Idaho

National Park Service, Craters of the Moon
Bureau of Land Management, Craters of the Moon
Wikipedia, Craters of the Moon National Monument and Preserve




The US Route 20 Blog homepage can be found here.