 Political Map  The northern Pacific Coast  The Pacific Mountain System |
The land.
Political Map
The northern Pacific Coast
The Pacific Mountain System
Relief.
Washington has seven physiographic regions. In the northwest the Olympic Peninsula borders the Pacific Ocean south of the Strait of Juan de Fuca. Dense rain forests extend along the western slopes of the rugged Olympic Mountains, which rise to 7,965 feet (2,428 meters) on Mount Olympus.
The Willapa Hills parallel the coast from Grays Harbor to the Columbia River in the southwest. Gentle, forested slopes descend to an indented Pacific coastline and to the Chehalis and Cowlitz valleys on the north and east.
The Puget Sound Lowland stretches southward from Canada between the Olympic Mountains and the Cascade Range to join the Chehalis and Cowlitz valleys, which form an extension to the Columbia River. Deep waters and fine harbors in Puget Sound, together with relatively flat terrain along its shores, favor the densest population and greatest commercial development in the state.
The Cascade Range, east of the Puget Sound Lowland, has the state's highest elevations. Its chain of volcanic peaks includes 14,410-foot (4,392-meter) Mount Rainier, the fifth highest peak in the coterminous United States. Mount St. Helens, located in the Cascades near the Oregon border, erupted violently in 1980. The highest peaks have permanent glaciers.
The Columbia Basin occupies most of central Washington, surrounded by the Cascades to the west, the Okanogan Highlands to the north, uplands to Idaho on the east, and the Blue Mountains to the southeast. A basalt plateau, lying at about 1,000 to 2,500 feet above sea level, it is drained by the Columbia River and its main tributary, the Snake. Glaciation, flooding, and wind have shaped diverse landforms, although the general appearance is that of a large interior plain.
The Okanogan Highlands, in the northeast, are an extension of the Rocky Mountains. Their north-south ranges, with summits that rise to more than 7,000 feet (2,100 meters), are separated by glaciated trenches. Most of the state's metallic ores are found in this region.
The Blue Mountains, which extend into Washington from Oregon, consist of uplifted
plateaus and ranges in the southeast corner of the state. Gentle slopes and broad valleys descend from 6,000-foot
(1,800-meter) heights to the Columbia Basin. Outliers to the west comprise the Horse Heaven Hills and Rattlesnake
Hills.
Soils.
The most productive soils in Washington are those of the river floodplains and the
weathered basalts and windblown silts of the Columbia Basin. In wetter areas acidic soils support forests, but
the driest regions east of the Cascades have sparse plant life and require irrigation for agriculture. The fine-textured
soils of the Big Bend and Palouse areas are susceptible to erosion by wind and water.
Climate.
Prevailing westerly winds and the influence of the Pacific Ocean dominate the climate of Washington, although the Cascades barrier creates significant differences between western and eastern regions. The west has milder conditions than any part of the United States at the same latitudes. Seattle has an average January temperature of 41° F (5° C) and a 66° F (19° C) July average. Annual precipitation on the Pacific slopes of the Olympic Peninsula exceeds 150 inches (3,810 millimeters), but places on the northeast of the peninsula (Port Angeles) receive less than 20 inches (508 millimeters) a year. From the Puget Sound Lowland, where 30-40 inches are typical annual totals, amounts increase again to more than 100 inches in the Cascades.
East of the Cascade Range seasonal temperature variations are greater, but the Rocky Mountains to some extent shield the region from cold Canadian air masses in winter. Maximum summer temperatures usually exceed 100° F (38° C) a few days each year. Spokane's January average temperature is 25° F (-4° C); the July average is 70° F (21° C). Annual precipitation is 17 inches (430 millimeters) at Spokane but less than eight inches (200 millimeters) in the lower valley.
Throughout the state precipitation is greatest in the cooler months, when a succession
of cyclonic storms move inland from the North Pacific, sometimes with gale-force winds. Rain falls on a great number
of days even in areas that are relatively arid, such as in the west. The occasional outbreaks of continental air
from the north or northeast may reach the outer coast, bringing freezing conditions in winter or hot, dry air that
increases the danger of forest fires in summer.
Plant and animal life.
Washington's 23,000,000 acres (9,308,000 hectares) of forest are among the most extensive in the United States. Major tree species are Douglas fir, hemlock, western red cedar, and ponderosa pine, found mainly in the mountain regions. On the semiarid parts of the Columbia Basin, grasses prevail, merging into sagebrush and other scattered shrubs in the driest areas.
Deer, elk, bears, mountain goats, and pumas (cougars) are among the large mammals, and there are also several fur-bearing animals. The Pacific flyway, a major route of North American waterfowl migration, follows the Puget Sound Lowland. Freshwater game fish include trout, bass, grayling, and sturgeon. Five species of Pacific salmon ascend western Washington streams to spawn. The coastal bays and Puget Sound are habitats for shellfish.
Settlement patterns.
About three-fourths of Washington's people live in urban areas, principally in the Puget Sound Lowland. More than 50 percent live in the Seattle and Tacoma metropolitan areas. Spokane is the largest city east of the Cascades and the focus of the "inland empire," a large economic region of agriculture, forestry, and mining that reaches to northeastern Oregon, northern Idaho, western Montana, and southern British Columbia, Can. Smaller cities of eastern Washington include agricultural trade centers such as Wenatchee, Yakima, and Walla Walla. The Tri Cities area (Richland-Kennewick-Pasco) at the confluence of the Snake and Columbia rivers forms a transportation center for irrigated agriculture, manufacturing, and the Hanford Site (an atomic energy installation).
Typical towns of the eastern wheat lands are crowned by grain elevators, whereas food processing plants are common in the towns that serve irrigated farms. Lumber towns and small mining settlements are found along the upland margins of the Columbia Basin.