Hart Bridge, Cantilever bridge in Jacksonville, Florida, United States.

Hart Bridge is a steel cantilever bridge, a type of continuous truss bridge, carrying U.S. Route 1 Alternate and State Road 228 over the St. Johns River in Jacksonville. Its main span is unusual for a cantilever bridge: the truss over the main channel tapers upward and the roadway below hangs from it on steel hangers. Designed by Sverdrup & Parcel, it is painted green.

The bridge was built in 1967 and named after Isaiah Hart, who founded Jacksonville. It became a key infrastructure connection between the downtown area and southern parts of the city.

Locals call the green-painted span "The Green Monster". The highway it carries from downtown to Beach Boulevard is the Commodore Point Expressway, known locally as the Hart Bridge Expressway.

The bridge carries US 1 Alternate and SR 228, and the highway stretch from downtown to Beach Boulevard is locally called the Hart Bridge Expressway. Traffic averages 52,000 vehicles a day, so crossings are busiest at commute times.

The bridge's main span is unusual for a cantilever bridge: the truss over the main channel tapers upward, and the roadway hangs below it on steel hangers. In 1999 it was ranked 19th among the longest cantilever bridges in the world.