Rochester is a city in Olmsted County, Minnesota, United States, and its county seat. It is located along rolling bluffs on the Zumbro River's south fork in Southeast Minnesota. At the 2020 census, the city had a population of 121,395, making it Minnesota's third-most populous city. The Rochester metropolitan area, which also includes the nearby rural agricultural areas, had a population of 226,329 in 2020. The city is the home and birthplace of Mayo Clinic.