Sugar River may refer to:
The Sugar River is a 26.0-mile-long (41.8 km) river in Roscommon and Gladwin counties in the U.S. state of Michigan. It is a tributary of the Tittabawassee River, which flows to the Saginaw River.
The Sugar River is a tributary of the Pecatonica River, approximately 91 miles (146 km) long, in the U.S. states of Wisconsin and Illinois.
It rises in the hills of southwest Wisconsin, in southwest Dane County, approximately 15 miles (24 km) southwest of Madison. The headwaters are at the southern terminus of the last North American glacier. West of the river, the land elevates from lack of glaciation and joins what is known as the "driftless area", known for its abrupt hills and valleys, covering most of southwest Wisconsin. From its source, the river meanders southeast, past Paoli and Belleville, where it is dammed to form Lake Belle View. From there it meanders east of Monticello where it is joined by the Little Sugar River and flows south through Albany, and Brodhead. It crosses into northern Illinois flowing past an extensive area of the Winnebago County Forest Preserve system. These preserves are Sugar River Alder, Colored Sands, and Sugar River. The river joins the Pecatonica River in northern Winnebago County near Shirland, approximately 5 miles (8 km) south of the state line and approximately 15 miles (24 km) north-northwest of Rockford.