The Main Street Bridge, officially the John T. Alsop Jr. Bridge, is a bridge crossing the St. Johns River in Jacksonville, Florida. It was the second bridge built across the river. It carries four lanes of traffic, and is signed as U.S. Route 1/US 90 (SR 5/SR 10). A lift bridge, it opened in July 1941 at a cost of $1.5 million] In 1957 it was named after Mayor John T. Alsop, Jr., but continues to be known, even on road signs, as the Main Street Bridge.