Here is a thrifty, yet nifty, way to reinforce geography for littles.
Learn geography through the mail by means of postcards. Have friends, family, and Internet contacts send postcards from their hometown, field trips, and vacations to your children.
Hang up a big map of the U.S. in your home. When a postcard comes, find it's origin on the map and mark it with a pin. Or, you could hole punch the postcard, tie yarn through the hole, and then tack it to the state or city from which it came.
Try to get postcards from all 50 states. If you're ambitious, go global and set up a world map. And make sure that you reciprocate by sending out your own postcards.
The added bonus is that you stay in contact with all your loved ones.