Carrollton, the seat of Carroll county, is located on the Ohio River at the mouth of the Kentucky River. The area was settled in the late eighteenth century and the town was established in 1794 as Port William, named probably for William Porter, an early settler. Port William was the seat of Gallatin county (formed in 1798) until 1838 when Carroll county was formed. Port William was made the seat of the new county and renamed Carrollton. The Port William post office opened in 1807 and was renamed Carrollton in 1838. The population in 1990 was 3,715.