Oregon ( (listen)) is a state in the Pacific Northwest region of the United States. Oregon is a part of the Western United States, with the Columbia River delineating much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. The 42° north parallel delineates the southern boundary with California and Nevada. The western boundary is formed by the Pacific Ocean.

Oregon has been home to many indigenous nations for thousands of years. The first European traders, explorers, and settlers began exploring what is now Oregon's Pacific coast in the early to mid-16th century. As early as 1564, the Spanish began sending vessels northeast from the Philippines, riding the Kuroshio Current in a sweeping circular route across the northern part of the Pacific. In 1592, Juan de Fuca undertook detailed mapping and studies of ocean currents in the Pacific Northwest, including the Oregon coast as well as the strait now bearing his name. The Lewis and Clark Expedition traversed Oregon in the early 1800s, and the first permanent European settlements in Oregon were established by fur trappers and traders. In 1843, an autonomous government was formed in the Oregon Country, and the Oregon Territory was created in 1848. Oregon became the 33rd state of the U.S. on February 14, 1859.

Today, with 4.2 million people over 98,000 square miles (250,000 km²), Oregon is the ninth largest and 27th most populous U.S. state. The capital, Salem, is the second-most populous city in Oregon, with 177,723 residents. Portland, with 652,503, ranks as the 26th among U.S. cities. The Portland metropolitan area is the 25th largest metro area in the nation, with a population of 2,512,859.

Oregon is also one of the most geographically diverse states in the U.S., marked by volcanoes, abundant bodies of water, dense evergreen and mixed forests, as well as high deserts and semi-arid shrublands. At 11,249 feet (3,429 m), Mount Hood, a stratovolcano, is the state's highest point. Oregon's only national park, Crater Lake National Park, comprises the caldera surrounding Crater Lake, the deepest lake in the United States. The state is also home to the single largest organism in the world, Armillaria ostoyae, a fungus that runs beneath 2,200 acres (8.9 km²) of the Malheur National Forest.

Oregon's economy has historically been powered by various forms of agriculture, fishing, logging, and hydroelectric power. Oregon is the top lumber producer of the contiguous United States, with the lumber industry dominating the state's economy during the 20th century. Technology is another one of Oregon's major economic forces, beginning in the 1970s with the establishment of the Silicon Forest and the expansion of Tektronix and Intel. Sportswear company Nike, Inc., headquartered in Beaverton, is the state's largest public corporation with an annual revenue of $46.7 billion.