When the Black Men of Labor Social Aid & Pleasure Club parade, the first major second line of the fall season, began on Sunday, September 3, over two thousand people gathered on St. Claude Avenue in front of jazz club Sweet Lorraine’s, undeterred by the blazing afternoon heat.

Most noticeable were the club members themselves, about 15 in number, dressed to the nines in matching outfits: green and white sash, vanilla slacks, light-green...