The Smolen–Gulf Bridge is a covered bridge which carries State Road (Ashtabula County Road 25) across the Ashtabula River at the Plymouth and Ashtabula Township line in northern Ashtabula County, Ohio, United States. At 613 feet (182.9 meters), it is the longest covered bridge in the United States – a title formerly held by the Cornish–Windsor Covered Bridge in New Hampshire – and the fourth longest covered bridge in the world.