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 (Juniperus virginiana) 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 (as it was still called) 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.