The valley of the Willamette River in western Oregon is the most densely populated and agriculturally productive region of the state, and is home to eight of the ten most populous cities. Oregon's 2000 population was about 3.5 million, a 20.3% increase over 1990; it is estimated to have reached 3.8 million by 2008. Oregon's largest for-profit private employer is Intel, located in the Silicon Forest area on Portland's west side.

Oregon enjoys a diverse landscape including the windswept Pacific coastline, the volcanoes of the rugged and glaciated Cascade Mountain Range, dense evergreen forests, and high desert across much of the eastern portion of the state. The tall Douglas firs and redwoods along the rainy Western Oregon coast contrast with the lower density and fire prone pine tree and juniper forests covering portions of the eastern half of the state. Stretching east from Central Oregon, the state also includes semi-arid scrublands, prairies, deserts, and meadows. Mount Hood is the highest point in the state at 11,249 feet (3,429 m). Crater Lake National Park is the only national park in Oregon.

Humans have inhabited the area that is now Oregon for at least 15,000 years. In recorded history, mentions of the land date to as early as the 16th century. During the 18th and 19th centuries European powers and later the United States quarreled over possession of the region until 1846 when the U.S. and Great Britain finalized the division of the region. Oregon became a state in 1859 and is now home to over 3.5 million residents.

Human habitation of the Pacific Northwest began at least 15,000 years ago, with the oldest evidence of habitation in Oregon found at Fort Rock Cave and the Paisley Caves in Lake County. Archaeologist Luther Cressman dated material from Fort Rock to 13,200 years ago. By 8000 B.C. there were settlements throughout the state, with populations concentrated along the lower Columbia River, in the western valleys, and around coastal estuaries.

By the 16th century Oregon was home to many Native American groups, including the Bannock, Chasta, Chinook, Kalapuya, Klamath, Molalla, Nez Perce, Takelma, and Umpqua.

The first European explorers were Spanish, during the late 17th Century. Further exploration from Alta California took place during the 18th century. British James Cook explored the coast in 1778 in search of the Northwest Passage.

The Lewis and Clark Expedition traveled through the region also in search of the Northwest Passage. They built their winter fort at Fort Clatsop, near the mouth of the Columbia River. Overland exploration was also conducted by British explorer David Thompson.

In 1811, David Thompson, of the North West Company, became the first European to navigate the entire length of the Columbia River. Stopping on the way, at the junction of the Snake River, he posted a claim to the region for Great Britain and the North West Company. Upon returning to Montreal, he publicized the abundance of fur-bearing animals in the area.

Also in 1811, New Yorker John Jacob Astor financed the establishment of Fort Astoria at the mouth of the Columbia River as a western outpost to his Pacific Fur Company; this was the first permanent European settlement in Oregon.

In the War of 1812, the British gained control of all of the Pacific Fur Company posts. The Treaty of 1818 established joint British and American occupancy of the region west of the Rocky Mountains to the Pacific Ocean. By the 1820s and 1830s, the Hudson's Bay Company dominated the Pacific Northwest from its Columbia District headquarters at Fort Vancouver (built in 1825 by the District's Chief Factor John McLoughlin across the Columbia from present-day Portland).