How did the revival of Evangelical mass baptisms such as those loosely portrayed in media such as Oh Brother, Where Art Thou and Bioshock Infinite come about? Was the movement in response to specific occurrences in American social politics at the time? What were the main movements, and who were the primary leaders?
Thanks in advance for any answers. Let me know if I can clarify my question.
OP, since no one has answered yet:
Two terms you may wish to explore on your own are "The Great Awakening" (there's been more than one, your period is generally considered the third) and "Muscular Christianity" -- which may or may not eventually lead you to the history of Graham crackers.
To the rest of AskH:
I realize my answer may not fit your criteria; feel free to remove. OP's question asks for basics that are well-covered in many sources (and I've tried to help point her/him there.)
If I might tag on -- have there been any changes in the way these movements are seen? Are there emergent thoughts about them, or current controversies?