One of the best ways to get a "feel" for the different periods of recent U.S. history is to look at the films produced during these periods. Frank Capra's
Why We Fight series is a particularly good source for understanding both America's pre-war isolation and the transformation of the United States into the mightiest military machine in all history.
A good source for certain aspects of the following Cold War period is the
Atomic Cafe documentary.
Please watch portions of either one (or both) of these documentaries. Comment here on your impressions: what did you get from watching the films that you might not have understood from just reading or listening to a lecture?