The current route was built along the original right of way of the Overseas Railroad, which shortened the driving distance between Florida City and Key Largo by nearly 14 miles (23 km).

The United States Navy, which continues to have a large presence in Key West, sought an improved access to the mainland during World War II, which is the reason the Overseas Highway was rerouted onto the former railroad right of way.

The current Card Sound Bridge opened in 1969, restoring the original route and giving the Florida Keys two vehicular accesses to the mainland.

[1] The Jewfish Creek drawbridge was replaced by the current bridge on May 22, 2008, as a part of larger $300 million project to reconstruct the entire stretch of U.S. 1 between Florida City and Key Largo.

In addition to the drawbridge, the current bridge allowed for the removal of the Lake Surprise Causeway, which dated back to the days of the railroad, restoring the natural water flow into Florida Bay.