Waterloo is a city located in Jefferson County in the U.S. state of Wisconsin. As of the 2000 census, the city had a total population of 3,259. The city is located within the Town of Waterloo along the Maunesha River.
The city is home to the headquarters of Trek Bicycle Corporation, one of the world's leading bicycle producers.
Waterloo is located at 43°11'1" North, 88°59'23" West (43.18366, -88.989965).
According to the United States Census Bureau, the city has a total area of 10.2 km2 (3.9 mi2). 10.1 km2 (3.9 mi2) of it is land and 0.1 km2 (0.04 mi2) of it is water. The total area is 0.51% water.