Stumbled upon a nifty resource today while searching - these!
Dimensions of this puzzle are 17 inches x 17 inches. Here's what the manufacturer says about these puzzles:
"GeoPuzzles are jigsaw puzzles that make learning world geography fun. The pieces of a GeoPuzzle are shaped like individual countries, so children learn as they put the puzzle together. Award-winning Geopuzzles help to build fine motor, cognitive, language, and problem-solving skills, and are a great introduction to world geography for children 4 and up. Designed by an art professor, jumbo sized and brightly colored GeoPuzzles are available for 5 major continents. "
So, you can work on Latin America, Asia, Africa and the Middle East, and Europe along with the U.S. and Canada. I think you could be 105 and still get something out of putting one of these together.