The American West PBS |American Experience
Now here is something. PBS supports its American West series (how did I get this old and educated with no idea who Kit Carson was), with web presentations and the American Frontiers Map.
Starting just down the trail from here, where the French and Indian War began with a young Major named Washington, George, at Fort Necessity; the American Frontiers map is a graphic introduction to a very wide range of resources. Click on "Northwest Territory, you'll see the 5 state area, and be taken to the interactive document page at ourdocuments.gov. Some introduce learners to new sites at the Library of Congress. Many links take you to the topic sites at pbs.org.
Its a wonderful integrative interactive--the kind I wish I'd invented.