Mask use was spotty among customers as casinos in Reno, Las Veegas and throughout Nevada reopened Thursday for the first time since March following a closure to prevent the spread of the coronavirus. Casino resorts closed in mid March. By April, unemployment reached 28.2%, topping figures in any state even during the Great Depression. Casino winnings were near zero. Alan Feldman, a longtime casino executive who is now a fellow at the International Gaming Institute at the University of Nevada, Las Vegas, called reopening an extremely important moment. “This is going to be a pretty long, slow climb,” he said.