Much of the west pretty much doesn't bother with the rest of the continenet and pursues their own agendas. This is especially true in the Northwest of America. Tucked in between the Cascadian Mountains and the Pacific Oceans are a group of rival and independent city states like Seattle, Portland and Vancouver. Because most of the citizens are connected to coast or river, the climate is extremely mild, and the resources are bountiful, no particular community can assert dominance.
Like is counterpart, the United States of America, the Northwest city states are a very maritime and a trade-based culture. They're situated very well between mineral rich mountains and timber-heavy forests, and are a very convenient stop between the tundras of Alaska and the deserts of California. The major difference being that Cascadia is not a united empire. Cascadia also nothing to do with the Non-Denominational Church, its citizens are Buddhists.
Because the culture revolves around a harmonious balance with nature, some of the outlying villages and hamlets may build around the very tall trees that make up the temperate rainforests. Farms and a few other places are still located on the ground, but it's strategically advantageous to garrison troops on the the ground, and very few people have to worry about flooding caused by the area's constant rain.
In the region's prosperity and wealth though, the Northwesterners have become ambitious, and sought out to expand. The merchants will support this for the opportunity of trading rights, and to keep the more belligerent war-mongers out of their hair. The most successful attempt at expanding has been along the Columbia river, forging the new kingdom, the District of Columbia.