The Anderson River is a 50.4 miles (81.1 km) tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Ohio River

Ohio River

The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...

 in southern Indiana

Indiana

Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Via the Ohio, it is part of the watershed

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 of the Mississippi River

Mississippi River

The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

.

The Anderson rises in western Crawford County

Crawford County, Indiana

Crawford County is a county located in the U.S. state of Indiana. As of 2010, the population was 10,713. The county seat is English.-Geography:...

 in the Hoosier National Forest

Hoosier National Forest

The Hoosier National Forest, in the hills of south central Indiana, is a property managed by the United States Forest Service. Composed of four separate sections, it has a total area of . It is headquartered in Bedford, with a regional office in Tell City...

 and flows generally southwardly through southeastern Dubois County

Dubois County, Indiana

Dubois County is a county located in the U.S. state of Indiana. The county seat is Jasper. As of 2010, the population was 41,889.Dubois County is part of the Jasper Micropolitan Statistical Area.-History:...

 and along the common boundary of Perry

Perry County, Indiana

Perry County is a county located in the southwestern part of the U.S. state of Indiana. As of 2010, the population was 19,338. The county seat is Tell City. It is the hilliest county as well as one of the most forested counties of in Indiana as it features more than of Hoosier National Forest...

 and Spencer

Spencer County, Indiana

As of the census of 2000, there were 20,391 people, 7,569 households, and 5,752 families residing in the county. The population density was 51 people per square mile . There were 8,333 housing units at an average density of 21 per square mile...

 counties, past the town of Saint Meinrad. It joins the Ohio River just downstream of the town of Troy

Troy, Indiana

Troy is a town in Troy Township, Perry County, Indiana, along the Ohio River near the mouth of the Anderson River. The population was 392 at the 2000 census.-Geography:Troy is located at ....

.

Near its mouth it collects the Middle Fork Anderson River, which flows for its entire length in Perry County.