Four decades ago, against the unlikely backdrop of a city in full prep-mode for the 1984 World’s Fair, Mayor Ernest “Dutch” Morial announced the city would host a small festival in the French Quarter in April, a few weeks before the World’s Fair was set to open in May.

At the time, downtown New Orleans was under siege. Construction sites had taken over the riverfront. The Central Business and Warehouse Districts were a jumble of construction nightmares and traffic jams. And in the French Q...