Discuss the Louisiana Purchase. How did it come about? Who were the driving forces

Discuss the Louisiana Purchase. How did it come about? Who were the driving forces etc? This is a useful link http://www.encyclopediaofarkansas.net/encyclopedia/entry-detail.aspx?entryID=2383

http://www.youtube.com/watch?v=iMpAZEWLmec

This video features Dr. Joseph Key from Arkansas State University as well as some other very notable Arkansas Historians.