Oregon's geography may be split roughly into seven areas:
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Oregon Coast—west of the Coast Range
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Basin and Range Region
The mountainous regions of western Oregon were formed by the volcanic activity of Juan de Fuca Plate, a tectonic plate that poses a continued threat of volcanic activity and earthquakes in the region. The most recent major activity was the 1700 Cascadia earthquake; Washington's Mount St. Helens erupted in 1980, an event which was visible from Portland.
The Columbia River, which constitutes much of the northern border of Oregon, also played a major role in the region's geological evolution, as well as its economic and cultural development. The Columbia is one of North America's largest rivers, and the only river to cut through the Cascades. About 15,000 years ago, the Columbia repeatedly flooded much of Oregon during the Missoula Floods; the modern fertility of the Willamette Valley is largely a result of those floods. Plentiful salmon made parts of the river, such as Celilo Falls, hubs of economic activity for thousands of years. In the 20th century, numerous hydroelectric dams were constructed along the Columbia, with major impacts on salmon, transportation and commerce, electric power, and flood control.
Today, Oregon's landscape varies from rainforest in the Coast Range to barren desert in the southeast, which still meets the technical definition of a frontier.
Oregon is 295 miles (475 km) north to south at longest distance, and 395 miles (636 km) east to west at longest distance. In terms of land and water area, Oregon is the ninth largest state, covering 97,073 square miles (251,418 km²).
The highest point in Oregon is the summit of Mount Hood, at 11,239 feet (3,428 m), and its lowest point is sea level of the Pacific Ocean along the Oregon coast. Its mean elevation is 3,300 feet (1,006 m). Crater Lake National Park is the state's only National Park, and the site of Crater Lake, the deepest lake in the U.S. at 1,943 feet (592 m)Oregon claims the D River is the shortest river in the world, though the American state of Montana makes the same claim of its Roe River. Oregon is also home to Mill Ends Park (in Portland), the smallest park in the world at 452 square inches (about 3 square feet, or 0.29 m²).
Major cities and towns
Oregon's population is largely concentrated in the Willamette Valley, which stretches from Eugene (home of the University of Oregon, 3rd largest city) through Salem (the capital, 2nd largest) and Corvallis (home of Oregon State University) to Portland (Oregon's largest city.)
Astoria, at the mouth of the Columbia River, was the first permanent English-speaking settlement west of Rockies. Oregon City was the Oregon Territory's first incorporated city, and its first capital (from 1848 until 1852, when the capital was moved to Salem.) It was also the end of the Oregon Trail and the site of the first public library established west of the Rocky Mountains, stocked with only 300 volumes. Bend, near the geographic center of the state, is one of the ten fastest-growing metropolitan areas in the United States. To the Southern part of the state, the Medford area is a rapidly growing metro area and culturally rich part of the state. It it home to The Rogue Valley International-Medford Airport, the third busiest airport in the state. Further to the south, near the California-Oregon border, is the community of Ashland, home of the Tony Award winning Oregon Shakespeare Festival.
Climate
Oregon's climate—especially in the western part of the state—is heavily influenced by the Pacific Ocean. The climate is generally mild, but periods of extreme hot and cold can affect parts of the state. Precipitation in the state varies widely: the deserts of eastern Oregon, such as the Alvord Desert (in the rain shadow of Steens Mountain), get as little as 200 mm (8 inches) annually, while some western coastal slopes approach 5000 mm (200 inches) annually. Oregon's population centers, which lie mostly in the western part of the state, are generally wet and soggy, while the high deserts of Central and Eastern Oregon are much drier.