The day after the gun massacre at the First Baptist Church in Sutherland Springs, Texas, filmmaker Michael Moore—whose 2002 documentary “Bowling for Columbine” tackled that watershed mass shooting—took note of a particular fact. “As of yesterday,” he told his millions of Twitter followers, “Columbine is no longer one of the 10 worst mass shootings in US history.” CNN had already published the full score card: “2 of the 5 deadliest mass shootings in modern US history happened in the last 35 days,” announced the headline.