Decatur, Ohio

Decatur is an unincorporated community in eastern Byrd Township, Brown County, Ohio, United States. It has a post office with the ZIP code 45115. It is located along State Route 125, an east-west highway.

Decatur was originally called St. Clairsville, and under the latter name was laid out around 1802. A post office called Decatur has been in operation since 1817.