The shortest of three state routes that lie completely within Ashtabula County, the current SR 85 is a fraction of the route it was when first designated in the mid-1920s, when it ran from Euclid to Andover and onto the Pymatuning Causeway. When US 6 was designated in Ohio in the early 1930s, SR 85 was at first co-signed with the U.S. highway from Euclid to Andover, but by the late 1930s, the SR 85 shields were removed from this stretch of roadway, leaving just the stretch of highway that exists today.