Edgerton is a city in Rock County and partly in Dane County in the U.S. state of Wisconsin. The population was 5,461 at the 2010 census. Of this, 5,364 were in Rock County, and 97 were in Dane County. Known locally as "Tobacco City U.S.A.," because of the importance of tobacco growing in the region, Edgerton continues to be a center for the declining tobacco industry in the area. Social issue.