There's a sort of symmetry between natural and human geography in the heart of south-central Washington's Mid-Columbia Basin. Here, three great rivers run together--the Columbia, the Snake, and the Yakima--and here three cities edge that confluence zone. These are the Tri-Cities: Pasco, Kennewick, and Richland, each with their own history, feel, and character, to be sure, but so close and intertwined that they merge into one of the most significant urban areas on the mostly rural (and often remote) Columbia Plateau. The proximity to those rivers and the availability of aquifer water in this lava-layered basin explain the siting of the Tri-Cities and their deep agricultural roots amid a semi-arid country of barren ridges (including the Horse Heaven Hills just south) and steppes. This windswept landscape was epically scoured and washed over by the many editions of the Ice Age-era Missoula Floods: geological drama seemingly out of step with today's subdued topography.
Close to some of the oldest verified archaeological sites in North America, this place also stands as the traditional homeland of a number of native Plateau peoples, including the Yakama, Walla Walla, Umatilla, and Cayuse. In its early decades of Euro-American settlement, the Tri-Cities area became embroiled in one of the most intense conflicts between American Indians and white colonizers in the Pacific Northwest, the Yakima War of the 1850s--a far cry from the relatively peaceful interactions between indigenous cultures and Lewis and Clark, whose Corps of Discovery passed through this region in 1805. (Corps of Discovery-related historical sites in these parts include Sacagawea State Park in Pasco and Bateman Island at the mouth of the Yakima.)
The Tri-Cities began as farming and railroad towns in the mid- to late 1800s, and remained mostly off the national radar till the 1940s, when the U.S. government established the Hanford nuclear site to the near north. Much of Hanford (in the midst of an ongoing cleanup project) remains strictly off-limits, but you can explore some rare pristine Columbia Basin shrub-steppe and the last free-flowing stretch of the Columbia River (the White Bluffs) in the Hanford Reach National Monument.
Today the Tri-Cities remain an important hotbed of agriculture--including, notably, viticulture, which has patterned the countryside with vineyards alongside all the orchards and wind farms. The metro area has also emerged as a corporate center and a popular place for young professionals and families as well as retirees to settle. Long a shopping hub for the surrounding region, the Tri-Cities also increasingly serve as a destination for arts and culture. It's a unique corner of the Inland Northwest, a waypost for cross-country travelers but also a conglomerated cityscape that rewards fine-focused investigation.