Pasco (/ˈpæskoʊ/ PAS-koh) is a city in, and the county seat of, Franklin County, Washington, United States. It had a population of 59,781 at the 2010 census, and 75,432 as of the July 1, 2019 Census Bureau estimate.

Pasco is one of three cities (the others being Kennewick and Richland) that make up Washington state’s Tri-Cities region, a mid-sized metropolitan area of approximately 296,224 people.

On October 16, 1805, the Lewis and Clark Expedition camped in the Pasco area, at a site now commemorated by Sacajawea State Park. The area was frequented by fur trappers and gold traders. In the 1880s, the Northern Pacific Railway was built near the Columbia River, bringing many settlers to the area. Pasco was officially incorporated on September 3, 1891. As Pasco is located in Southeastern Washington, the city lies in the rain shadow of the Cascade Range. As a result, the area is a windswept desert, receiving little precipitation throughout the year.