The horror of mass shootings, up 26 percent in the last decade, has become almost routine. The news from Oregon was grim enough in isolation – nine people shot dead at a community college. For many Americans it was all the sadder as a reminder of how frequent, how depressingly routine, mass shootings have become – in malls, at churches, and so often at schools and colleges. In Loveland, Colorado, an elementary school principal mused wistfully on how security precautions now preoccupy her staff, including adults-only evacuation drills that exempt the students so as not to traumatize them.