segment of the Pacific mountain system of western North America. The Cascades extend northward for more than 700 miles (1,100 km) from Lassen Peak, in northern California, U.S., through Oregon and Washington to the Fraser River in southern British Columbia, Can. Many peaks exceed 10,000 feet (3,000 m), including Mount Hood (Hood, Mount) (11,235 feet 【3,424 m】, highest point in Oregon) and Mount Rainier (Rainier, Mount) (14,410 feet 【4,392 m】, highest in Washington and in the Cascade Range). Most of the summits are extinct volcanoes, but Lassen Peak (10,457 feet 【3,187 m】) and several others have erupted in the recent past. Mount Baker (10,778 feet 【3,285 m】) steamed heavily in 1975, and Mount St. Helens (Saint Helens, Mount) (8,365 feet 【2,550 m】) erupted in 1980 and again in 1981. The mountains lie 100 to 150 miles (160 to 240 km) inland from the Pacific Ocean and east of the broad depressions known as the Puget Sound Lowland and the Willamette Valley, which separate the moist coastal region from the arid interior. They are continued by the Coast Mountains of British Columbia to the north and the Sierra Nevada to the south.

Marked by glaciation (which has formed many lakes) and stream dissection, the mountains are a headstream region for the Willamette River. Except for the peaks lying above the timberline, the entire range is heavily wooded and is within conservation areas and national forests. The western slope, fed by up to 100 inches (2,500 mm) of precipitation yearly, has dense stands of Douglas fir trees. North Cascades, Mount Rainier, Crater Lake, and Lassen Volcanic national parks, as well as Lava Beds National Monument and Manning Provincial Park (Canada), offer unusual natural formations and magnificent scenery. Tourism, outdoor recreation, and water for hydroelectric power, irrigation, and industry are the main activities and assets of the range.

The English navigators George Vancouver and William R. Broughton saw the Cascades in 1792. The American explorers Meriwether Lewis and William Clark, on their expedition to the northwest in 1806, passed through the range in the 4,000-foot- (1,219-metre-) deep Columbia River Gorge on the Washington-Oregon border. The range was named for the great cascades found near the gorge.