Oregon

I

Introduction

Oregon, one of the Pacific coast states of the United States, bordered on the north by Washington; on the east by Idaho; on the south by Nevada and California; and on the west by the Pacific Ocean. The Columbia River forms much of the northern boundary.

Oregon entered the Union on February 14, 1859, as the 33rd state. Encompassing a land area of great topographical diversity and scenic beauty, it has traditionally had an economy based on agriculture and the exploitation of its vast forests. In the 1990s manufacturing and service industries were also very important. The origin of the state name is uncertain. It may, however, be derived from the French ouragan, meaning “hurricane”, a name formerly applied to the Columbia River. Oregon is also known as the “Beaver State”.

II

Land and Resources

Oregon has an area of 251,470 sq km (97,093 sq mi) and is roughly rectangular in shape; its extreme dimensions are 476 km (295 mi) from north to south and 669 km (416 mi) from east to west. Elevations range from sea level to 3,426 m (11,239 ft) at the top of Mount Hood. Oregon’s coastline along the Pacific Ocean is 476 km (296 mi) long.

A

Physical Geography

Oregon has considerable physiographic diversity. The state can be divided into seven geographical regions: the Coast Ranges, the Klamath Mountains, the Willamette Valley, the Cascade Range, the Columbia Plateau, the Blue Mountains, and the Great Basin. The Coast Ranges lie along much of the Pacific coast. Lower than the coastal mountains of California or Washington, they have a maximum elevation of about 1,219 m (4,000 ft). To the south lies a small portion of the granitic Klamath Mountains. To the east lies the Oregon portion of the Cascade Range: a sloping volcanic tableland, capped by a series of presently dormant volcanoes, including Mount Hood, the Three Sisters, and Mount McLoughlin.

Covering much of the eastern half of the state is the Columbia Plateau. A unique portion of this region is the Blue Mountains; with elevations exceeding 2,743 m (9,000 ft). To the south of the Columbia Plateau lies a portion of the Great Basin. A region of basins separated by low-lying mountains, the Great Basin is internally drained.

The Columbia River, forming most of the Oregon-Washington boundary, is the principal river of the state. Its major tributary, the north-and-west flowing Snake River, forms part of the state’s north-eastern boundary and joins the Columbia River in Washington. Other important rivers are the Willamette, Deschutes, Rogue, Umpqua, and Klamath.

The state has numerous natural lakes, especially in the Cascade Range, although none of these is large. Crater Lake, the most famous, lies in the crater of an ancient, extinct volcano. To the south-east is the larger Klamath Lake; to the east are the shallow Harney and Malheur lakes.

B

Climate

Western Oregon has an equable, humid climate, dominated by marine influences; east of the Cascade Range the climate is dry and continental, characterized by greater daily and seasonal temperature extremes. In coastal areas the average temperature of the coldest month is only 8.3° C (15° F) lower than that of the warmest month; in the Columbia Plateau the difference is 22.2° C (40° F). The recorded temperature has ranged from -47.8° C (-54° F) in 1933 to 48.3° C (119° F) in 1938. Although the west is cool, humid, and cloudy, summers are dry. The western slopes of the Cascades receive 7,620 to 12,700 mm (300 to 500 in) of snow a year.