To the roar of cannons and fire works bursting in air, Montreal's Expo 67, last week closed down the turnstiles to what had been, by almost all measures, the most successful world's fair in history. In the surge of last-day crowds, souvenir hunters made off with a guitar autographed by the Beach Boys from the U.S. pavilion and a nativity crib from the West German pavilion. But no amount of petty vandalism could sully Expo's singular triumph: in just six months the fair had racked up a total attendance of 50 million*20 million more than had been expected.
Statistically, Expo was...