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Willamette(wĭlăm`ət), river, 294 mi (473 km) long, rising in several headstreams in the Cascade Range, W Oregon. It flows N past Eugene, Salem, and Portland to the Columbia River just NW of Portland. The river is navigable for most of its course. Its wide, fertile valley is a major fruit-growing and dairying region. There is also diversified agriculture, manufacturing, and an important lumber industry. A federal project begun in 1938 harnesses the river and its tributaries for flood control, navigation, and power production with numerous dams and reservoirs in the Willamette basin. First settled in the 1830s, the valley was the goal of many pioneers traveling west to the Oregon Country on the Oregon Trail. The region quickly became the chief source of food products on the West coast, especially with the California gold rush in the mid-1800s. Rapidly settled after 1846, the valley has long been the most densely populated part of Oregon.
a river in the western USA; a left tributary of the Columbia River. Rising in the Cascade Mountains, the Willamette River is 480 km long and drains an area of 27,700 sq km. The mean flow rate is 1,040 cu m per sec. There is a hydroelectric power plant on the river, which is navigable as far as the city of Eugene, Ore. Salem is on the Willamette, and the seaport of Portland is situated at the river’s mouth.