The ONLY USA maps I've been able to find that actually work for this one covers only a smattering of mid-western states and the map data (read: POI) is pretty old.
Unable to find ANY maps that work with it for the SouthEast, East, NorthWest, SouthWest, etc. Only thing that works is pretty much Kansas/Missouri in a tiny "corridor" west out to LA. Most of California and the entire US isn't even covered in that map and switching to any of the other USA map files (S-EAST.prm, EAST.prm, etc) gives one the dreaded "resource files missing, reinstall application" error message forcing one to delete the prefs.ini file in the system/app/route66 folder on the memory card to get it to select the lame "North America.prm" file which barely has anything in it.

Route 66: Great if you live/travel in Europe, horrible if you live/travel anywhere else.