For a year now Jeanie and I have used Pocket Earth downloaded on our I-pad for traveling. For $2.99, one-time-only payment, upgradable, you can download maps of the world! I loaded about 20 states onto the I-pad for use on an around the U.S. circumnavigation, but we have used it over and over again. The downloaded maps are interactive and have a locator that follows you around (via the gps on the I-pad) whether you are on line or not. You can telephoto in very closely or pull way out to get a bigger picture and all kinds of info pops up. It's not quite as good as the very expensive NatGeo maps that it pushed right out of the market, but all that info for that price...hard to beat. I have no association with Pocket Earth.
jefe
http://pocketearth.com/