The Pacific Northwest (in the United States, commonly abbreviated as PNW), sometimes referred to as Cascadia, is a region in western North America bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Though no agreed boundary exists, a common conception includes the U.S. states of Oregon, Washington State, and the Canadian province of British Columbia. Broader conceptions reach north into Alaska and Yukon, south into the coastal and mountainous regions of Northern California, and east into Idaho and Western Montana, western Wyoming, and western Alberta, to the Continental Divide. Narrower conceptions may be limited to the Northwestern U.S. or to the coastal areas west of the Cascade and Coast mountains. The variety of definitions can be attributed to partially overlapping commonalities of the region's history, geography, society, and other factors.
The Northwest Coast is the coastal regions of the Pacific Northwest and the Northwest Plateau (also commonly known as "The Interior" in British Columbia and the Inland Empire in the United States) is the inland regions. The term "Pacific Northwest" should not be confused with the Northwest Territory (also known as the Great Northwest, a historical term in the United States) or the Northwest Territories of Canada.
The region's largest metropolitan areas are Greater Seattle, Washington State, with 3.9 million people; Greater Vancouver, British Columbia, with 2.4 million people; and Greater Portland, Oregon, with 2.2 million people.