I think the entire 9XX range of units has had both N.A. and Europe maps combined. That and sometimes an inertial navigation device for tunnels were the only real differentiators between the 9XX and equivalent 7XX series.
You should find a configuration item under settings for Manage Maps.
When you get the unit to the U.S., do be aware that you've just confused the heck out of the poor thing, and it may well take some minutes to realize where it is, and pull down almanac data appropriate to the satellites in view in your new location.