http://www.nps.gov/cham/forteachers/Flip-Book.htm
This is an interesting flipbook map as it shows the change of the Rio Grande in a specific area over time. The Rio Grande serves as part of the established border between Mexico and The United States of America. So it's interesting to see how a national border goverened by a river can change it's location over time as the course of th river changes over time.