DISASTERS: The Violent, Deadly Swath of Agnes

THE most ravaging storm in U.S. history started as a tiny blip on radar screens, a knot of tropical air masses forming near the island of Cozumel in the Gulf of Mexico, a few miles east of the Yucatan peninsula. Quickly, awesomely, it built into the first hurricane of the year, christened Agnes, a turbulent mass 250 miles in diameter drawing unusually heavy amounts of moisture from the sea below.

First Agnes crashed through Florida and Cuba and seemed about to peter out as it moved inland. But then it turned out to...