So, I found a great source of historical imagery from Buffalo, NY. The coolest part is watching the NY State Thruway (I-90) getting built from south of Walden Dr (open space that's now the Walden Galleria Mall) to about Main St (NY 5), as well as the old downtown.
I'm wondering why Google Earth hasn't found sources like this to use? They also have a 1920's version of the region. I haven't seen anything that old on Google Earth yet.
Sets also exist for Detroit and other areas. It would be nice to see Google update to include more sources.