The Great Miami River (also called the Miami River) is a tributary of the Ohio River, approximately 160 mi (257 km) long, in southwestern Ohio in the United States.

It rises in Indian Lake in Logan County, approximately 15 mi (24 km) SW of Lima. It flows S and SW, past Sidney, and is joined by the Loramie River in northern Miami County. It flows south past Piqua and Troy, and through Dayton, where it is joined by the Stillwater and the Mad rivers and Wolf Creek .

From Dayton it flows SW past Middletown and Hamilton in the southwestern corner of Ohio. In southwestern Hamilton County it is joined by the Whitewater River approximately 5 mi (8 km) upstream from its mouth on the Ohio, on the Ohio-Indiana state line, approximately 15 mi (24 km) west of Cincinnati.

The river is named for the Miami, an Algonquin-speaking Native American people who lived in the region during the early days of white settlement.

The Miami and Erie Canal built in the 1830s connected the upper reaches of the river with Lake Erie and served as the principal route of transportation for western Ohio until the 1850s.

Following a catastrophic flood in March, 1913, the Miami Conservancy District was established in 1914 to build dams and levees and to dredge and straighten channels to control flooding of the river.

The region surrounding the Great Miami River is known as the Miami Valley.

See also

• Little Miami River
• List of Ohio rivers