Topographical maps, like the one above, provide a wealth of information on the built and natural environment in a particular place. On these maps you will find a host of information on such things as the transportation system in an area (railroads, roads and highways, airports), the power system (through the presence or absence of electrical lines) the extent of forests and fields, and the location of buildings and structures - from sewerage disposal plants to homes to drive-in movie theatres. Because of this, these maps are a wonderful primary source for historians - they preserve an image of an area at one point in time. Since historians are concerned with change over time, we can literally SEE change over time on the landscape by comparing earlier versions of these maps with subsequent versions. And that is your assignment, compare at least three versions of the same map, record the changes you see in your place, and make some preliminary assessments as to why those changes have taken place.
Your assignment: "Select, analyze and write about change over time"
If you REALLY want to get involved, go to this website (http://terraserver.microsoft.com/default.asp) and locate your area. This site has more up to date topographical maps, so you may be able to see even more change than from the maps at UNH. The images from these maps are of rather poor quality however, so I would not rely on them too much.