The Seven Mile Bridge is 6.765 miles long and 38 feet wide, with a clearance of 65 feet. The design used with precast concrete, as a segmented box girder bridge.
Currently, there are two bridges, an older and a modern version. The older bridge was constructed from 1909-1912 as part of the Florida East Coast Railway and known as the Overseas Railroad or Knights Key-Pigeon Key-Moser Channel-Pacet Channel Bridge. In 1935, the Labor Day Hurricane damaged the railroad and the railway was sold to the U.S. government which restored it for vehicle use.