When the Old Seven Mile Bridge was built, it was an engineering wonder of the early 1900s. Part of Henry Flagler’s famous railway to Key West, it ran across nearly seven miles of open water to connect Marathon to the Lower Keys.
One of the longest bridges when it was built, The Seven Mile Bridge connects Knight’s Key where the city of Marathon is located in the Middle Keys to Little Duck Key in the Lower Keys. Almost true to its name, The piling-supported concrete bridge is 35,862 ft or 6.79 miles (10.93 km) long. The current bridge bypasses Pigeon Key, A section of the old bridge still remains for access to the island.
After the railroad sustained considerable damage due to effects of the Labor Day Hurricane of 1935, the line was sold to the United States Federal Government, who subsequently refurbished Seven Mile Bridge for automobile use. Dismantled trackage was recycled, painted white, and used as guardrails. It had a swing span that opened to allow passage of boat traffic, near where the bridge crosses Pigeon Key, a small island where a work camp for Flagler’s railroad was located. Hurricane Donna in 1960 caused further damage.
The current road bridge was constructed from 1978 to 1982. The vast majority of the original bridge still exists, used as fishing piers and access to Pigeon Key, but the swing span over the Moser Channel of the Intracoastal Waterway has been removed.