Five states form the Pacific States region of the United States - Alaska, California, Hawaii, Oregon and Washington - and, as its name suggests, they all have coastlines on the Pacific Ocean (and are the only states that border that ocean). Additionally, Nevada and Arizona are sometimes included despite the fact that neither of these states actually border the Pacific. This is primarily because of strong ties that each state and their respective metropolitan areas have to neighboring California. The division is one of two that are located within the United States Census Bureau's Western region; the other such division is the Mountain States.

The Northwest Coast of the Early and Middle Holocene of prehistory consists of the Pacific coastline from the mouth of Copper River in Alaska to the Klamath River in northern California. The forager societies mainly consisted of hunter-gatherers whose most popular source of food was salmon. The people of this time and place lived in planked houses that were small, and rectangular in shape. As the population of the Northwest Coast grew, social hierarchies were formed. Leadership was often given to shamans or kin leaders. They also had people low enough in their society to be enslaved. A factor in the size of the population was that of temperature. Within the last 5000 years, temperature has fluctuated greatly, bringing on the Medieval Warm Period as well as the Little Ice Age.

Despite being slotted into the same region by the Census Bureau, the Pacific and Mountain divisions are vastly different from one another in many vital respects, most notably in the arena of politics: While nearly all of the Mountain states are regarded as being conservative "red states", all of the Pacific states except Alaska are clearly counted among the liberal "blue states." Indeed, the other division with which residents of the Pacific States are seen as most closely self-identifying is New England, where many of the Pacific States' seminal settlers actually hailed from: Portland, Oregon was named after Portland, Maine, and according to John Molloy, author of the 1980s-era bestseller Dress For Success, businessmen in San Francisco display virtually identical sartorial preferences as their counterparts in Boston.