I've reached the point where I think I've scanned through most of Sam's 
life and located most of the important locations. Suggestions, 
additions, etc always welcomed.

https://twainsgeography.com/gazetteer

Yes, there is much to be done.  Styling etc is inconsistent.  The only 
section  of this web project I consider to be "done" is the 1895 North 
American Tour.  This is where I started, with the idea of creating an 
on-line course in historical geography.  For the most part I think of 
this site as a large box of index cards.