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The Willamette Valley ( ) is the region in northwest Oregonmarker in the United Statesmarker that surrounds the Willamette River as it proceeds northward from its emergence from mountains near Eugenemarker to its confluence with the Columbia River at Portlandmarker. A small part of the Willamette Valley ecoregion is in southwestern Washingtonmarker, around the city of Vancouvermarker. Being a productive agricultural area, the valley was the destination of choice for the emigrants on the Oregon Trail in the 1840s. It has formed the cultural and political heart of Oregon since the days of the Oregon Territorymarker, and is home to 70% of Oregon's population.


The source of much of the Willamette’s fertility is derived from a series of massive ice age floods that came from Glacial Lake Missoulamarker in Montanamarker and scoured across Eastern Washington, sweeping its topsoil down the Columbia River Gorgemarker. When floodwaters met log-and-ice jams at Kalama, in southwest Washingtonmarker, the water caused a backup that filled the entire Willamette Valley to a depth of 300-400 feet above current sea level. Some geologists suggest that the Willamette Valley flooded in this manner multiple times during the last ice age, to depths of 300-400 feet. If 300-400 foot-deep floodwaters descended on the Valley today, in Portland (elevation 20 ft), only the tops of the West Hillsmarker, Mt. Tabor, Rocky Butte, Kelley Butte and Mt. Scott would be visible, as would some of the city’s skyscrapers, such as the US Bancorp Towermarker (530 feet) and the Wells Fargo Centermarker (540 ft). Newbergmarker’s elevation is 175 feet above sea level, Oregon Citymarker (138 ft), McMinnvillemarker (157 ft), Salemmarker (154ft), Corvallismarker (235 ft) and Eugenemarker (430 ft), likely rising above all of them. The lake gradually drained away, leaving layered sedimentary soils on the valley floor to a height of about 180-200 feet above current sea level throughout the Tualatinmarker, Yamhill and Willamette Valleys.

Geologists have come to refer to the resulting lake as Lake Allison. It was named for Oregon State Universitymarker geologist Ira S. Allison who first described Willamette Silt soil in 1953 and noted its similarity to soils on the floor of former Lake Lewis in Eastern Washington. Allison also is known for his work in the 1930s documenting the hundreds of non-native boulders (called Erratics) washed down by the floods, rafted on icebergs and deposited on the valley bottom and in a ring around the lower hills surrounding the Willamette Valley. One of the most prominent of these is the Bellevue Erraticmarker, just off Oregon Route 18 west of McMinnville.


The valley may be loosely defined as the broad plain of the Willamette, bounded on the west by the Oregon Coast Range and on the east by the Cascade Range. It is bounded on the south by the Calapooya Mountainsmarker, which separate the headwaters of the Willamette from the Umpqua River valley about south of Hidden Valley. Interstate 5 runs the length of the valley, linking its major communities.

Because of the differing cultural and political interests, the Portland metropolitan areamarker and Tualatin River valley are often not included in the local use of the term. Additionally, the east slopes of the Coast Ranges and the west slopes of the Cascade Range from Oakridgemarker to Detroit Lakemarker can be considered part of the Willamette Valley in a cultural sense, despite being mountainous areas.

Cities generally considered part of the Willamette Valley are Eugenemarker, Corvallismarker, Albanymarker, and Salemmarker. In its most expansive definition, the valley includes areas of Bentonmarker, Polkmarker, Yamhillmarker, Washingtonmarker, Clackamasmarker, Lanemarker, Linn, Marionmarker, and Multnomahmarker counties. Sometimes the area around Albany and Corvallis, and surrounding Benton and Linn counties is referred to locally as the Mid-Valley. Marion, Polk, and other counties are sometimes included in the definition of the Mid-Valley.


The Willamette Valley has a wet climate, with about 50 inches of rain a year. It is in between an oceanic climate and Mediterranean climate.

Summers are dry and somewhat warm, the rest of the year, from November to April is very wet. Snow is rare, with on average only one to three light falls a year, and a major snowstorm only a couple times a decade.


The agricultural richness of the valley is in part a result of the Missoula Floods, which inundated the valley approximately forty times between 15,000 and 13,000 years ago at the end of the last ice age. The floods were caused by the periodic rupturing of the ice dam of Glacial Lake Missoulamarker, the waters of which swept down the Columbia River and flooded the Willamette Valley as far south as Eugene. The floodwaters carried rich volcanic and glacial soil from Eastern Washington, which was deposited across the valley floor when the waters subsided. The soil in the Willamette Valley is about deep in some areas.

The major agricultural products of the valley include many varieties of berries and vegetables. The valley also produces most of the grass seed, Christmas trees, and hazelnuts sold in North America. It is also noted for its hops, which are widely used in craft beer and microbreweries throughout the U.S. But it is greenhouse and nursery stock that have become the biggest agricultural commodity in the valley.

Grass farmers have been burning fields, as part of their production, since the 1940s. The smoke is often irritating to residents, and in 1988, caused a 23 car pileup on I-5. Over the years, several pieces of legislation have limited the amount of burning permitted. With the passage of a bill championed by legislator Paul Holvey in the 2009 session, burning will be banned as of 2010, with the exception of about 15,000 specific acres with steep terrain and certain species. (At its peak in the 1980s, about 250,000 acres were burned each year.)

In recent decades, the valley has also become a major wine producer, with multiple American Viticultural Areas of its own. With a cooler climate than Californiamarker, the gently rolling hills surrounding the Willamette are home to some of the best (and most-expensive) pinot noir in the world, as well as a high-quality pinot gris. It is home to Eyrie Vineyardsmarker, winner of the pinot noir competition at the Wine Olympics held in Parismarker in 1979.


During the 19th century, the valley was largely inhabited by bands of the Kalapuya tribe of Native Americans. The Hudson's Bay Company controlled the fur trade in the valley and the rest of Oregon Country in the 1820s and 1830s from its Columbia District headquarters at Fort Vancouvermarker. Joint U.S. - British occupancy, in effect since the Treaty of 1818, ended in 1846 with the Oregon Treaty.

The Willamette Valley was connected to California's Central Valleymarker by the Siskiyou Trail. The first European settlements in the valley were at Oregon Citymarker and Champoegmarker. The first institution of higher learning on the West Coast, today's Willamette Universitymarker, was founded in the valley at Salem by Jason Lee, one of the many Oregon missionaries that settled in the valley.


The Willamette Valley

The Willamette Valley is prone to periodic floods. Notable floods include events in 1899, 1964, and the Willamette Valley Flood of 1996. Part of its floodplain is a National Natural Landmark called the Willamette Floodplainmarker.

North Pacific Oak Woodland is a major forest alliance, extending through the Willamette Valley and southward to the Klamath Range of Northern California. Many of the soils are well drained mesic.

Popular culture

David Brin's book The Postman (which was adapted into a film of the same name) is largely set in the Willamette Valley, aka Hidden Valley, mostly around the town of Corvallismarker.

The Willamette Valley appears, quite fittingly, at the end of The Oregon Trail computer game as the blanket destination.

S. M. Stirling’s The Emberverse series takes place mainly in the Willamette Valley when technology suddenly fails. Portland and Corvallis both figure heavily in the series.

In the movie A League of Their Own, directed by Penny Marshall, Geena Davis's and Lori Petty's characters are discovered playing softball and living on a dairy farm in the fertile Willamette Valley. The Davis character eventually returns to her life there.

In the Terry Brooks novel series The Genesis of Shannara, the elf land of Cintra is located in Willamette.

The 1986 film Stand by Me was largely filmed in Brownsville, Oregonmarker, a historic town in the midst of the Willamette Valley.. The unspoiled and natural beauty appears in many scenes, helping to establish the mood of the 1950s.

See also


  1. Loy, William G. "Atlas of Oregon" (2001) University of Oregon Press, Eugene, OR. pp. 35 ISBN 0-87114-102-7.
  2. Cataclysms on the Columbia, by John Elliott Allen and Marjorie Burns with Sam C. Sargent, 1986. Pages 175-189
  3. Geology of Oregon, by Elizabeth L. Orr, William N. Orr and Ewart M. Baldwin, 1964. Pages 211-214
  4. Hazelnut Production (8/26/96), USDA NSS report
  5. C.Michael Hogan (2008) Quercus Kelloggii,, ed. N. Stromberg [1]

Further reading

  • Elma MacGibbons reminiscences of her travels in the United States starting in 1898, which were mainly in Oregon and Washington. Includes chapter "Willamette Valley."
  • O'Connor, J.E., et al. (2001). Origin, extent, and thickness of Quaternary geologic units in the Willamette Valley, Oregon [U.S. Geological Survey Professional Paper 1620]. Reston, VA: U.S. Department of the Interior, U.S. Geological Survey.

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