The Cascade Range is a 1,130 km (700 miles) long mountain chain that extends south from British Columbia (Canada) to northern California (United States). In California it becomes the Sierra Nevada. The Cascade Range parallels the Coast Ranges, but lies further inland, between 160 and 240 km (100 - 150 miles) from the Pacific Ocean.

Many of the Cascade Range's highest peaks are volcanic cones that are covered with snowfields and glaciers. One of these peaks is Mount Saint Helens, which erupted in 1980 in one of the greatest volcanic explosions in U.S. history. Another active volcano is 3,187 m (10.457 feet) high Lassen Peak in Lassen Volcanic National Park. The highest point in the Cascades is Mount Rainier, which rises 4,392 m (14,410 feet) above sea level. It is in Mount Rainier National Park. Other prominent peaks are Mount Shasta and Mount Hood.

The Columbia River flows from east to west across the range and there are countless lakes. Crater Lake, in Crater Lake National Park and Lake Chelan, in Lake Chelan National Recreation Area, are the most famous. Other federal lands in this popular recreation area are North Cascades National Park, Ross Lake National Recreation Area and Cascade-Siskiyou and Lava Beds national monuments. Large parts of the region are covered by national forests.

The Cascade Range is a major source of water in the northwestern United States, because the mountain range receives more than 254 cm (100 inches) of precipitation annually, much of it as snow. On the range's western slopes, hydroelectricity is generated, while irrigation is used in the fertile eastern side valleys. Timber is the region's chief resource, but a growing concern for ecology and the environment has developed into a major political debate surrounding the trees. The Cascade Tunnel also crosses the mountain range. It is one of the longest railroad tunnels in North America, having a length of 12.9 km (8 miles).