Kennewick is a city in Benton County in the southeastern part of the U.S. state of Washington, near the Hanfor nuclear site. It is the most populous of the three cities collectively referred to as the Tri-Cities (the others being Pasco and Richland). Kennewick is located along the southwest bank of the Columbia River, opposite Pasco and just south of the confluence of the Columbia and Yakima rivers. The population was 54,693 at the 2000 census.