It was not just two people, it was led by Lewis and Clark but was a sizable group. Here's a link to a list of all the members of the Expedition, including ones who joined later (such as Sacagawea) or deserted. Also lists Lewis's dog Edit, sorry, Here's the link http://www.lewisandclark.org/wiki/index.php?title=Expedition_Members Not sure why it didn't show the first time.