Located on the west end of Bahia Honda Key, the bridge was originally built between 1905 and 1912 by Henry Flagler as part of the Overseas Railroad. It was intended to carry a single track of the Florida East Coast Railway across the Big Spanish Channel from Bahia Honda Key to Spanish Harbor Key. Due to the channel’s depth, being 24-feet at it’s deepest point, the Bahia Honda Bridge was built with a steel truss construction as opposed to a concrete arch form that was predominate throughout the Overseas Railway.
The bridge was damaged during the Labor Day Hurricane of 1935 to the point that the FEC sought to abandon it before it was purchased by the State of Florida. Rather than rebuilding the bridge, the existing foundations were repaired and was converted to become part of the Overseas Highway in 1938 by adding the deck on top of the existing truss. The bridge served as the primary mode of transport to the lower keys and as the main evacuation route.
In 1980, a new four-lane bridge was constructed just a few hundred yards north of the old bridge, replacing the old route. Two of the truss spans of the old bridge were later removed to allow boat traffic.
The original bridge still remains, though it has fallen into a state of disrepair and signs warning boats of falling debris. Maintained by Bahia Honda State Park, the easternmost section of the bridge is open to pedestrian traffic and provides a scenic overview of the area.