- Ken Burns' documentaries and his new book all show his love for U.S. history
- The renowned filmmaker has met the six most recent U.S. presidents
- Many of America's early presidents played key roles in creating pristine national parks
As the National Park Service turns 100 in 2016, CNN has launched a yearlong series celebrating the parks' incredible natural wonders and historical sites.
(CNN)When Ken Burns' daughters were little, they played a game of memorizing the names of the presidents at bedtime.