2009 takes 1 disc.
Huh? I have a 2009, and it requires 2 discs to cover the entire US. Granted, only one is used at a time, but part of the map is on one disc and the other part is on the other disc...I probably should have clarified that, so maybe this is just semantics. Again, not a big deal unless you happen to live / work on the boundary of a the map split.