According to my local newsweb (www.mbl.is) Air Force One has been in use since December 1972. During that period it has made a total of 444 trips and travelled about 1 million miles. In those 29 years it has served 6 presidents (Gerald Ford, Jimmy Carter, Ronald Reagan, George Bush, Bill Clinton & George W. Bush).
Here is a photo taken today after the last trip (from Waco to San Antonio).
Reykjavik Aviation Photography - Just bring the aircraft to us and we'll photograph them! :-)