Sun Valley and Ketchum are in Idaho's Wood River Valley, gateway to backcountry and wilderness areas.

Settlers first arrived in the early 1880s, attracted by a silver rush. In 1883, the railroad connected the valley to the world beyond its borders and brought in outside capital. During the silver depression of the 1890s, mining was replaced by sheep raising, and the area later shipped more sheep than anywhere except Australia. In 1936, during the Great Depression, Union Pacific board chairman Averell Harriman built Sun Valley, the country's first destination ski resort, spending $2.5 million in two years ($45 million today). Sun Valley offered a lavish lifestyle, a luxurious lodge, Austrian ski instructors, and chairlifts invented by Union Pacific engineers. Known as America's St. Moritz, it was a magnet for beautiful people and serious skiers. It had a monopoly on grandeur for decades and influenced ski areas that developed later. Subsequent owners Bill Janss and the Holding family expanded and improved Sun Valley, making it one of the world's premier year-round resorts.