In hard-hit South Florida, beaches from Palm Beach to Key West will be shut down for the Fourth of July holiday weekend. (AP Photo/Lynne Sladky)The U.S. headed into the Fourth of July weekend with many parades and fireworks displays canceled, beaches and bars closed, and health authorities warning that this will be a crucial test of Americans' self-control that could determine the trajectory of the surging coronavirus outbreak. The fear is that a weekend of crowded pool parties, picnics and parades will fuel the surge. The warnings were sounded after a Memorial Day weekend that saw many people emerge from stay-at-home orders to go to the beach, restaurants and family gatherings. Dr. Don Williamson, head of the Alabama Hospital Association, said he is really, really worried about the Fourth of July."