Complete article, here.
“WaPo points to a study by Mother Jones that claims that high-profile shootings began increasing in gun-free zones in late 2011/early 2012. The examples Mother Jones provides are the Aurora movie theater, Sandy Hook Elementary, and the D.C. Navy Yard, all of which were gun-free zones.
Other examples of shootings in gun-free zones that could have been cited are Arapahoe High School (December 2013), Fort Hood (April 2014), Emanuel African Methodist Episcopal Church (June 2015), Chattanooga military offices (July 2015), the Lafayette Grand Theatre (July 2015), and Umpqua Community College (October 1).”
All things and recent events considered, this sign would be more effective: