Great Miami River
![](/Images/godic/202501/16/Great_Miami_River0948.jpg")
![Map of the watersheds of the Great Miami River (beige) and Little Miami River (yellow).](/Images/godic/202501/16/MiamiRivers_watershed0948.png")
![Flannery Island, located in the mouth of the Miami at its confluence with the Ohio River](/Images/godic/202501/16/Flannery_Island_at_Ohio-Miami_confluence0948.jpg")
The Great Miami River (also called the Miami River) (Shawnee: Msimiyamithiipi ) is a tributary of the Ohio River, approximately 160 miles (260 km) long, in southwestern Ohio and Indiana in the United States. The Great Miami flows through Dayton, Piqua, Troy, Hamilton, and Sidney.