What did Lewis and Clark achieve?

Their expedition was the first to accurately report on the width of the American continent. Know one, before Lewis and Clark, knew exactly the size of the continent from east to west coast. They made notes on the flora and fauna, and took as many samples as they could. They made maps and named rivers, streams, and geographical landmarks. By exploring all the way to the Pacific, they established America's claim to the Northwest Territories. They met and recorded the various Indian tribes and their locations. They reported on the riches of the area and opened up the west for future exploration, study, and settlement.