Hartford, the seat of Ohio county, is located at the junction of US 231 and KY 69 at the Rough River. It was settled by 1790 and named Fort Hartford, probably for a deer crossing of the river. It was made the seat when Ohio county was formed in 1798. Hartford was incorporated in 1808. The Hartford Court House post office opened in 1801. The population in 1990 was 2,532.
The first Ohio County Courthouse, of logs, was built in 1800. The present structure, the fourth, was built in 1940.