The Hemisphere: Geographical Surgery Gives the U.S. & Canada a New Artery

THE ST. LAWRENCE SEAWAY

WHILE a sharp summer thunderstorm crackled across the St. Lawrence Valley, crowds of raincoated tourists scrambled to the crest of a high dirt dike near Cornwall. Ont. one morning last week and peered through the mist toward a stubby earthen dam 2½miles away. At 7:55 a warning rocket arched overhead, and a voice on a loudspeaker began a countdown. An engineer in a timbered bunker pressed a button; from the explosive-mined dam a yellow curtain of debris belched upward toward the thunderheads. Deliberately, the blasted dam crumbled, and muddy...