Rochester is a city in the U.S. State of Minnesota and is the county seat of Olmsted County. Located on the Zumbro River's south fork, the city has a population of 106,769 according to the 2010 United States Census. The U.S. Census Bureau estimated that the 2015 population was 112,225. It is Minnesota's third-largest city and the largest city located outside of the Minneapolis-St. Paul-Bloomington Metropolitan Statistical Area.