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What does this map show? It relies on the wind patterns of an average spring day, in that particular decade. That decade was the 1960s, and about the biggest worry to be carried on those spring winds: fallout. This map projects fallout, if an “enemy” were to drop 3,000 megatons on various military, industrial, and civilian targets at the same time, both ground detonations and air bursts. From the Saturday Evening Post, 23 March 1963.