Watertown is a city in Jefferson and Dodge counties in the U.S. state of Wisconsin. The population was 22,926 at the 2020 census, of which 14,674 were in Jefferson County and 8,252 were in Dodge County. Division Street, several blocks north of downtown, marks the county line. Watertown is a principal city of the Watertown–Fort Atkinson micropolitan statistical area which is in turn a sub-market of the larger Milwaukee–Waukesha–Racine combined statistical area.