Hadn't a clue.
You could say that even the Indians didn't discover America.
Trade networks apparently existed (by the goods found) which brought copper in from Michigan, Abalone shell from the west coast, Mica from the Carolinas, other materials up from the Gulf, etc.
Judging from point typologies I and others found on the West Virginia/Virginia border which ranged from Savanah River types from the Carolinas to point types from PA and NY, and other mid-continent types from further west, it is fair to say that extensive trade networks existed moving goods all over the continent.
If Lewis and Clark could travel to the ocean from St. Joe, you can bet it had already been done by traders moving goods from tribe to tribe. Primary trade routes were rivers, not interstates, but many later roads followed overland trails used by the indigenous residents long before.