Pasco (păsˈkō) [key], city (1990 pop. 20,337), seat of Franklin co., SE Wash., on the Columbia River near its confluence with the Snake and Yakima rivers. It is a trade and shipping center for the Columbia basin project. Farm products include wheat, alfalfa, potatoes, beans, grapes, and cattle. There is food processing and meatpacking; wineries and diverse manufacturing, including paper and machine parts, are also important. Pasco was an early railroad division point. With Kennewick and Richland it forms a tricity area that grew during World War II, when the Manhattan Project's Hanford Works were constructed nearby. The completion (1956) of the McNary Dam extended Columbia River navigation to the mouth of the Snake River, thus making Pasco an inland port.