The ford at Ballykenny over the Camlin River left no visible trace at the surface, yet its former existence is recorded on one of the most ambitious cartographic projects of seventeenth-century Ireland, the Down Survey of 1655 to 1656. Commissioned under the direction of William Petty to map land confiscated following the Cromwellian conquest, the Down Survey captured not just townland boundaries but the practical geography of movement: roads, rivers, and the points where travellers could cross them. On the map of Longford barony, this particular crossing was marked simply as 'The Ford', a label that suggests it was well-known enough to need no further description.

Fords were the default crossing points on Irish rivers for centuries before bridges became common, and their locations often determined where roads ran and where settlements grew. The Camlin River, which flows westward through County Longford before joining the Shannon, was shallow enough at this point to allow passage on foot or by horse. The Down Survey map records a routeway passing through, with the ford as a fixed node along it. A second ford named on the same map, where a routeway crosses the nearby Fallan River, suggests this part of Longford had a network of such crossing points serving local movement. When Ballykenny Bridge was built in the nineteenth century, it appears to have been placed at or close to the same spot, which is itself a form of continuity; the logic of the landscape that made the ford practical in 1655 would have made the same location sensible for a later bridge builder.