The Marais des Cygnes River is a principal tributary of the Osage River. It is about long, and runs through eastern Kansas and western Missouri in the United States. Via the Osage and Missouri rivers, it is part of the watershed of the Mississippi River. The name "Marais des Cygnes" means "Marsh of the Swans" in French. But the name actually comes from an Osage name “Mixa-ckau-tse” (where white swans are plentiful). It was probably so named because of the trumpeter and tundra swans that were plentiful here before the late 1800s. The river is notorious for flash flooding. The river is referenced in the song "The River" by Chely Wright.