Fillmore County is a county in the U.S. state of Minnesota. As of the 2020 census, the population was 21,228. Its county seat is Preston. Fillmore County is included in the Rochester metropolitan area.

The Root River flows for 80 miles (130 km) through the Driftless Area of southeastern Minnesota and is a tributary of the Upper Mississippi River. The Root River is formed by three branches, the North, South and Middle branches of the Root River and the South Fork Root River. It is an excellent river for canoeing and fishing. The gentle to moderate flowing river drops an average of 3.4 ft/mile from Chatfield, Minnesota, to its pour point in the Mississippi River into Navigation Pool 7 just south of La Crosse, Wisconsin and east of Hokah, Minnesota.