GARY, Ind. — This city was once a symbol of American innovation. The home of U.S. Steel’s largest mill, Gary, Indiana, churned out the product that built America’s bridges, tunnels and skyscrapers. The city reaped the rewards, with a prosperous downtown and vibrant neighborhoods. Gary’s smokestacks are still prominent along Lake Michigan’s sandy shore, starkly juxtaposed between the eroding dunes and Chicago’s towering silhouette to the northwest. But now they represent a city looking for a fres