I was up until 2:00 AM this morning experimenting with downloading orthophotos and opening them in ArcView.

If you go to the USGS to get orthos, or any other map product, they will redirect you to a commercial site where you have to pay for them. I found out in class that a lot of, if not all, states offer not just orthophotos but all kinds of digital cartography products. Contour lines. Roads. Railways. Land use. Hydrology. Census statistics. Toxic waste sites. Pipe lines. Soil types. Lighthouses. Various governmental boundaries. Etc. I found a ton of stuff at Ohio's Natural Resource Conservation Service site.

To practice, I downloaded four orthos of Toledo. I could see all of the criss-crossing sidewalks of the University of Toledo. Cool! Each ortho, I think, is 7.5 minutes by 7.5 minutes, and I only downloaded four of them.
(7.5 minutes x 8 = 60 minutes, or 1º.
Most USGS map products are either 7.5 x 7.5 minutes or 15 x 15 minutes, so to cover 1º x 1º with 7.5 minute maps you would need 64 of them. To do the same with 15 minute maps you would only need 16. Of course the 7.5 minute maps are larger scale, so their is more detail on those.)

I could just see Byrne Road. I was going to download some more so I could see Mom and Dad's house to the west, but the FTP server became unavailable, so I took that as a sign that it was time to go to bed.

The orthos are georeferenced, which means there is latitude and longitude information embedded in the image. ArcView takes this information and then puts the individual images together to form one big seamless mosaic picture. Cool!