The Pacific Northwest (PNW) is an area often defined as northwestern corner of the continental United States. Its boundaries are imprecise: the Pacific coast states of Washington and Oregon are always included, with Idaho a common addition. Extreme western Montana, near Missoula, is less frequently included.
A multinational view of PNW leads to the inclusion of southwestern British Columbia. This broader view may relate to the region's modern origins in the former Oregon Country.
In ecology, the PNW is restricted to the coastal region from Kodiak Island in Alaska south to northwest California, but not extending more than 50-100 km inland. That region is characterized by high rainfall and an oceanic climate with mild winters.
During the colonial period, various claims to the Pacific Northwest were made by Russia, Spain, and the United Kingdom. The United States established a claim following the exploration of the region by the Lewis and Clark Expedition. From the 1810s until the 1840s, modern-day Washington, Oregon, Idaho, and western Montana, along with most of British Columbia, were part of the Oregon Country, which was jointly administered by the United States and the United Kingdom after the Treaty of 1818. John McLoughlin of the Hudson's Bay Company was the de facto local political authority for most of this time.
This arrangement ended as U.S. settlement grew and Polk was elected on a platform of "Fifty-Four Forty or Fight"; after a war scare with the United Kingdom, the two nations negotiated the 1846 Oregon Treaty, partitioning the region along the 49th parallel and resolving most (but not all) of the border disputes.
British Columbia, the UK portion, joined the Dominion of Canada in 1871. The U.S. portion became the Oregon Territory; it was later subdivided into territories that were eventually admitted as states.
The Pacific Northwest is dominated by several mountain ranges, including the Coast Ranges, the Cascade Range, and the Rocky Mountains. Because of plentiful rainfall and a relatively low population density, it has:
The major cities of Vancouver, Portland, and Seattle all began as seaports supporting the logging, mining, and farming industries of the region, but have developed into major technological and industrial centers (such as the Silicon Forest), which benefit from their location on the Pacific Rim.
- Cascadia is a proposed name for an nation uniting all or part of the PNW.