Hot springs by region.
Hot springs don't stop at state lines. These six geographic regions of the western United States each have their own soaking character — from the forested Pacific Northwest to the desert Great Basin.
Forested river valleys west of the Rockies hold some of the country's best-loved soaking pools, from developed resorts to primitive riverside springs reached on foot. Wettest and greenest of the western hot-spring regions.
The Cascade volcanic arc runs from Mount Baker down through Oregon into northern California. Geothermally heated springs surface near its stratovolcanoes, often at the end of a hike through old-growth forest.
Along the range's steep eastern escarpment — the Owens Valley, Mono Basin, and Long Valley Caldera — geothermal water rises against a backdrop of the highest peaks in the lower 48.
The endorheic basin-and-range country of Nevada and its neighbors has the highest density of undeveloped desert hot springs in the United States — many are remote, primitive, and reached by dirt road.
Springs strung along the Continental Divide, from historic resort towns to backcountry soaks. The Rockies hold a mix of commercial spas and free primitive pools at high elevation.
The Greater Yellowstone ecosystem holds the largest concentration of geothermal features on Earth. Note that soaking is prohibited in most of Yellowstone National Park itself — most springs here are for viewing, with legal soaking found on surrounding national-forest land.