Amid the celebrations of American independence comes sobering news from Northeastern University criminologist James Alan Fox. July Fourth ranks annually as the most violent day of the year, his research shows. Since 2006, there have been five mass killings (of four or more victims) by gunfire on July 4, according to the Associated Press/USA TODAY/Northeastern University Mass Killings Database, the most extensive data source on the subject. The trend is affirmed by the Gun Violence Archive. Since 2014, there have been 58 mass shootings on July 4 resulting in four or more people injured or killed.
Two main causes are driving July Fourth violence, Fox says. “We know from my research and research of others that as the temperature rises, violent crime rates go up,” says Fox, who presides over the mass killings database. “The reason for that is partially the physiological effects of heat on our emotions and temperament—we have short fuses when it gets hot.