(Charles Trainor Jr | Miami Herald | The Associated Press) In this Sunday, Feb. 18, 2018, file photo, people wander among crosses on a mound in front of Marjory Stoneman Douglas High School, where 17 crosses honor the students and teachers killed in a shooting spree on Wednesday, Feb. 14. If you want to know where mass school shootings are most likely to occur, look no farther than small-town and suburban America.