The Library of Congress offers a collection of images that are free to use and reuse. The LOC blog recently featured a subset of that collection called Maps of Cities. Maps of Cities is one of two sets of historic maps available through the Free to Use and Reuse collection. The other set of maps is called Discovery and Exploration.
Both the Maps of Cities and the Discovery and Exploration collections contain about two dozen historic maps that you can download and reuse for free in any classroom project. All of the maps can be downloaded as JPEG files (three sizes available) and as GIFs.
Applications for Education
I have always loved looking at maps because they spark my imagination. Historic maps in particular make me wonder about what life was like in the places depicted in those maps. Those ideas can be used to spark research and writing projects. You could have students research life about the places depicted in the historic maps. You could also have students attempt to write some historical fiction based on the maps.
Another use for these historic maps is to overlay them on current imagery. That can be accomplished in Google Earth. In the following video I demonstrate how that works.