MANITOWOC, Wis.—Standing in the softly falling snow, staring at the colorful and brightly lit Christmas display, Barbara Bundy-Jost understood anew—there was just something special about that tree. “It was just lit up like a sparkling forest,” she recalled. “We were on our way one Christmas Eve to visit my mother, who lived overlooking the lake on 4th Street. We always turned on that street. We stopped the car. The snow was softly falling. We let the kids out and we all stood in the window and we talked about the tree that my grandmother had.” That tree was unlike most tannenbaums displayed in millions of American homes for Christmas. It was an aluminum tree, the artful product of this city’s rich manufacturing past, now on display in a store window. Its presence that night was like a welcoming lighthouse, beckoning ships to port. Over the next two decades, the aluminum …