Watertown is a city in Dodge and Jefferson counties in the U.S. state of Wisconsin. Most of the city's population is in Jefferson County. Division Street, several blocks north of downtown, marks the county line. The population of Watertown was 23,861 at the 2010 census. Of this, 15,402 were in Jefferson County, and 8,459 were in Dodge County.
Watertown is the largest city in the Watertown-Fort Atkinson micropolitan area, which also includes Johnson Creek and Jefferson.
Watertown was first settled by Timothy Johnson, who built a cabin on the west side of the Rock River in 1836. He was born in Middleton, Middlesex County, Connecticut, on the 28th of June, 1792. A park on the west side of the city is named in his honor. The area was settled to utilize the power of the Rock River, which falls 20 feet (6.1 m) in two miles (two 10-foot (3.0 m) dams).