Not I don't want to trump Sprout since I rarely put two posts on the same day, but I wanted to point out Google Street View.
If you haven't already played around with the program it allows you to walk through the streets of major US cities on Google Maps. They are up to about 30 or US cities now and Yosemite National Park.
Now admittedly, I have no idea how this helps a Canadian History teacher - but I'm sure Canadian cities can't be far off. There are also lots of historic sites to stop and gaze at as you roll around the streets, especially if you are teaching any American history courses.