The Cedar River is a 338-mile-long (544 km) river in Minnesota and Iowa. It is a tributary of the Iowa River, which flows to the Mississippi River. The Cedar River takes its name from the red cedar trees growing there, and was originally called the Red Cedar River by the Meskwaki. The first Mississippi steamboat reached Cedar Rapids, Iowa in 1844, and during the next decade, the Red Cedar was an important commercial waterway. The surrounding region is known officially as the Cedar River Valley, though it is more commonly referred to simply as the Cedar Valley. The stream is young geologically, and only in places where the glacial material has been removed is the underlying bedrock exposed.

The Iowa River is a tributary of the Mississippi River in the state of Iowa in the United States. It is about 323 miles (520 km) long and is open to small river craft to Iowa City, about 65 miles (105 km) from its mouth. Its major tributary is the Cedar River.