Oregon (/ˈɔrɨɡən/ ORR-ə-gən) is a state in the Pacific Northwest of the United States. It is bordered on its west by the Pacific Ocean, north by Washington, south by California, east by Idaho, and southeast by Nevada. The Columbia River delineates much of Oregon's northern boundary, the Snake River largely its eastern.
Oregon's area was inhabited by many indigenous tribes before traders, explorers, and settlers arrived. An autonomous government was formed in Oregon Country in 1843, Oregon Territory was created in 1848, and Oregon became the 33rd state on February 14, 1859.
It is the 9th largest and 27th most populous state. Its capital is Salem, third most populous of its cities. With 603,106 (2012 estimate) residents Portland ranks 1st in Oregon, and 28th in the U.S. Its metro population of 2,262,605 (2011 estimate) is 23rd. The Willamette River Valley in western Oregon is the state's most densely populated area, home to eight of the ten most populous cities.
Oregon's landscape is diverse, with a windswept Pacific coastline, volcano studded Cascade Mountains, abundant waterfalls, dense evergreen forests, mixed forests, and deciduous forests at lower elevations, and high desert sprawling across much of its east all the way to the Great Basin. The tall Douglas firs and redwoods along its rainy west coast contrast with the lighter timbered and fire-prone pine and juniper forests covering portions to the east. Abundant alders in the west fix nitrogen for the conifers; aspen groves are common in the east. Stretching east from central Oregon are semi-arid shrublands, prairies, deserts, steppes, and meadows. At 11,249 feet (3,429 m) Mount Hood is the state high point, Crater Lake National Park its only national park.