The Straight River is a tributary of the Cannon River, 55.6 miles (89.5 km) long, in southeastern Minnesota, United States. Via the Cannon River, it is part of the watershed of the Mississippi River, draining an area of approximately 450 square miles (1,200 km2) in an agricultural region.

The Cannon River a tributary of the Mississippi River flows 112 miles (180 km) from Shields Lake near Shieldsville to Red Wing in the U.S. state of Minnesota, where it joins the Mississippi River. It drains a watershed approximately 1460 square miles (3,780 km²) in size. The river flows through the counties of Le Sueur, Rice, Dakota, and Goodhue.