Where can I find free aerial imagery?

Aerial imagery can be very useful in the classroom, public meetings, and land management planning and for general historical purposes. Aerial photography is one type of geospatial data that may require a large monetary investment. However, there are sources from which you may be able obtain aerial imagery for your area free of charge.
Most states have participated in national and statewide imagery programs since the middle 1990s (some have been involved even longer). Many of these states provide free …