Walla Walla is the largest city and county seat of Walla Walla County, Washington, United States. It had a population of 31,731 at the 2010 census, estimated to have increased to 32,900 as of 2019. The population of the city and its two suburbs, the town of College Place and unincorporated Walla Walla East, is about 45,000.Walla Walla is in the southeastern region of Washington, approximately four hours away from Portland, Oregon, and four and half hours from Seattle. It is located only 6 mi (10 km) north of the Oregon border.

The Tri-Cities are three closely linked cities (Kennewick, Pasco, and Richland) at the confluence of the Yakima, Snake, and Columbia Rivers in the Columbia Basin of Eastern Washington. Each city borders one another, making the Tri-Cities seem like one uninterrupted mid-sized city. The three cities function as the center of the Tri-Cities metropolitan area, which consists of Benton and Franklin counties. The Tri-Cities urban area consists of the city of West Richland, the CDPs of West Pasco and Finley, as well as the CDP of Burbank, despite the latter being located in Walla Walla County. The official 2016 estimate of the Tri-Cities MSA population is 283,846, a more than 12% increase from 2010. 2016 U.S. MSA estimates show the Tri-Cities population as over 300,000. The combined population of the three principal cities themselves was 193,567 at the 2010 Census. As of April 1, 2016, the Washington State Office of Financial Management, Forecasting Division estimates the cities as having a combined population of 217,430.The Tri-Cities Airport is located in Pasco and provides the region with commercial and private air service. Pasco is the seat of Franklin County, while the other two cities are located in Benton County. In 2010, Kiplinger rated the Tri-Cities among the Top 10 best places to raise a family, and CNN/Money ranked the Tri-Cities one of the top 10 best bets for gains in housing value, due to its relatively stable economic conditions since the early 2000s.

Union County is one of the 36 counties in the U.S. state of Oregon. As of the 2010 census, the population was 25,748. Its county seat is La Grande.Union County comprises the La Grande, OR Micropolitan Statistical Area. It is one of the eight counties of eastern Oregon.

Waitsburg is a city in Walla Walla County, Washington, United States. The population was 1,217 at the 2010 census. Waitsburg has a unique city classification in Washington state, being the state's only city which still operates under its territorial charter.