THE boys will be at Three Forks in a couple of days. I'd better get out to meet them."
Whenever Bradley Smith checked the pins on his map and made this sort of announcement, his family knew it was time for him to shoulder his camera and set off on another expedition into the Northwest.
For "the boys" were Explorers Meriwether Lewis and William Clark. And Brad Smith had been assigned by TIME to retrace their journey, photographing each landmark just as they first saw it, at the same time of year and...