Basin

A river basin contains a network of creeks, streams and rivers whose waters empty into one large river. A river basin can be very large. For example, the Mississippi River basin covers 48% of mainland United States.

All the streams in a river basin are connected, like the branches of a tree to the trunk. The smallest creeks drain into medium-sized streams and rivers. The medium-sized streams and rivers drain into large rivers, such as the Ohio River, Missouri River, Illinois River or the Minnesota River. The large rivers all drain into the main river, the Mississippi.