Richland is a city in Benton County, Washington, United States. It is located in southeastern Washington at the confluence of the Yakima and the Columbia Rivers. As of the 2020 census, the city's population was 60,560. Along with the nearby cities of Pasco and Kennewick, Richland forms the Tri-Cities metropolitan area. The townsite was established in 1905 and incorporated as Richland in 1910. The U.S. Army acquired the city and surrounding areas in 1943 for the establishment of the Hanford nuclear site, part of the Manhattan Project during World War II. Richland was transformed into a bedroom community for Hanford workers and grew to 25,000 residents by the end of the war.