Rochester is a census-designated place (CDP) in Thurston County, Washington, United States. It was founded in 1852, and the 2020 census recorded its population at 6,064. According to the United States Census Bureau, the CDP has a total area of 2.3 square miles (6.0 square kilometers), all of it land. Rochester Schools had 2,105 students registered in the 2021-22 School Year.