A man is screened with a backscatter X-ray machine as travelers go through a security checkpoint at Los Angeles International Airport in 2011. Danny Moloshok/Reuters/Corbis hide caption

itoggle caption Danny Moloshok/Reuters/Corbis

The ramp to departures is blocked by emergency vehicles at the New Orleans International Airport on Friday night in Kenner, La. Jonathan Bachman/AP hide caption

itoggle caption Jonathan Bachman/AP

TSA agents, like this one at Chicago's Midway International Airport, discovered more than 2,000 firearms at the nation's airports last year — the overwhelming majority of them loaded, according to new data. Nam Y. Huh/AP hide caption

itoggle caption Nam Y. Huh/AP

A sign informs travelers about Millimeter Wave Detection technology used in full body scanners at Midway Airport in Chicago. The scanners produce less-revealing images than those that use X-rays. Scott Olson/Getty Images hide caption

itoggle caption Scott Olson/Getty Images