The major physical features of western North America continue unbroken into that giant head of land that is Alaska. The Great Plains of the U.S. Midwest extend to become the Mackenzie Lowlands and the North Slope, while the Rocky Mountains form an inland spine from deep in Mexico to the Brooks Range. West of the Rockies, a high plateau runs from British Columbia north through the interiors of Yukon and Alaska, then west to the delta of the Yukon River, where it dips into the Bering Sea.

To the west of this plateau, two parallel chains and an intervening depression can be traced all the way from Mexico to Alaska. The Sierra Nevada of California become in turn the Cascades of Oregon and Washington, the Coast Mountains of British Columbia, the St. Elias and Wrangell Mountains, the Alaska Range, and finally the Aleutian Range, which then sinks into the Pacific just short of Asia. Closer to the ocean, California’s Coast Range becomes the Olympic Mountains of Washington. Farther north, a string of islands from Vancouver to the Queen Charlottes and the Alexander Archipelago runs into the St. Elias Mountains, where the two chains unite into a jagged ice-capped knot.

In Alaska they divide again as the Chugach and Kenai Mountains swing southwest toward Kodiak Island. Between these parallel chains is a 3,000-mile-long depression starting with California’s Central Valley, then continuing with Puget Sound, the Inside Passage, the Susitna Basin in Southcentral Alaska, Cook Inlet, and Southwest Alaska’s Shelikof Strait.

Only four low-level breaks occur in the coastal mountains: the valleys of the Columbia, Fraser, Skeena, and Stikine Rivers. Most of the places described in this travel guide are within or near this mighty barrier, which contains the highest peaks, the largest glaciers, and most of the active volcanoes in North America.