President Barack Obama's announcement last week of a wide-ranging anti-violence plan in response to the Newtown, Connecticut, school shootings comes as many districts are adopting new and sometimes dramatic measures--including arming teachers and volunteers--intended to prevent similar tragedies in their own schools. School safety experts warn…

Identifying whether suicides in a region are due to characteristics of the residents living there or to some enduring feature of the region is difficult when using cross-sectional studies. To distinguish these factors, we compared the suicides of a region's residents with people who were temporarily visiting the region. Using U.S. death records…