Value Blindness
Meriwether Lewis was at one point within walkable distance of one of the greatest gold deposits in Helena, Montana. He missed the whole thing. In his mind, mammals, not minerals, were the greatest source of wealth the Rocky Mountains provided. He wasn’t even looking for gold. This was a blank spot in his thinking that he acquired from Thomas Jefferson since the Rockies were too far away for mining. Had he paid attention to the mineral deposits, he would have discovered one of the largest finds that existed during that time. This would have led to others discovering shorter and easier trails earlier. The timetable for Western development would have moved up a whole generation.