The Cedar River is a river in Minnesota and Iowa which is named after the juniper (also called "red cedar") trees growing there. According to the Black Hawk County Green Party, it has the highest nitrate levels of any river in the world. It is also sometimes called the Red Cedar River.

The 45 mile (72 km) long Cedar River is located in central western Washington, USA. It starts in the Cascade Mountains, and since 1912 has emptied into Lake Washington at Renton. (It had previously emptied into the Black River, but was diverted in hopes of avoiding another flood like the one that took place in 1911.)

Cedar River is a river in the U.S. state of Michigan, flowing though Clare County and Gladwin County.