North America had struck me as horribly crowded, but her billion people are clumped—is still wasteland, mountain and desert. We laid down a grid on North America to show how precisely we could hit—Mike felt that fifty meters would be a large error. We had examined maps and Mike had checked by radar all even intersections, say 105° W by 50° N—if no town there, might wind up on target grid . . . especially if a town was close enough to provide spectators to be shocked and frightened.