In 1972, American air travelers could stroll from curbside to gate without once flashing a boarding pass. Very few fliers were checked with metal detectors, much less forced to remove their shoes. Not coincidentally, 1972 also brought the tail end of a five-year hijacking epidemic, during which at least 130 commercial flights were seized in the United States. As I chronicle in The Skies Belong to Us, the men and women responsible for this final flurry of mayhem were so heedless toward human life and so audacious in their demands that the airlines and federal government had no choice but to turn airports into miniature police states. The mandatory physical screening of all passengers began on January 5, 1973.