Rough sketch
William Clark spent much of his later years as an Indian Agent - basically someone who acted as a liaison between the native americans and the U.S. government. Its easy to look back at Indian Agents as bad guys but it should be noted that many of them such as Clark worked hard to make sure the natives weren't exploited or booted off their land during the explosion of western expansion. In fact, Clark lost a bid to be Governor of Missouri because his opponents painted him as too friendly with the Indians.
This illustration for the Notable Missourian book on William Clark shows Clark and other officials meeting with native american leaders for a treaty signing. The Notable MIssourian book series is published by Truman State University Press.
Alternate rough sketch
Another alternative rough showing Clark meeting with an tribal leader. I ended up using a version of this for the chapter 5 artwork.
