From Wikipedia, the free encyclopedia.
The Willamette Valley is the Oregon region surrounding the Willamette River as it proceeds from south of Eugene, Oregon down river (and north) to Oregon City. In common use the valley ends when it reaches the urban growth boundary of the Portland metropolitan area; based on physical geography, the valley continues through the middle of Portland until it meets with the Columbia River. Its western boundary is defined by the Coastal Range; its eastern, by the Cascade Range.
The Willamette Valley is home to nearly 20% of Oregon's population (or 60% if the Portland area is included). It was also the destination of many who traveled the Oregon Trail.
The valley forms one of the most productive agricultural regions in the world. For example, it produces most of the grass seed sold in North America.
The agricultural richness of the valley is considered to be in no small measure 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 Missoula, the waters of which swept down the Columbia 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.
In recent decades, the valley has also become a major wine producer, with an AVA of its own. With a cooler climate than California, the gently rolling hills surrounding the Willamette are home to some of the best pinot noir in the New World, as well as a high-quality pinot gris.
The valley includes three entire counties:
as well as parts of four others: