Posting this question on the Transportation Board would have netted very different responses. This questions comes up quite often, and many of the posters there have the facts close at hand.
darlak I am quite certain can relate her experience when she posted the question, and the responses which she received.
OP, why don't you post it there as well, and people can give you the facts like crashbb did. It may require some extra time and effort, but one can fly on a domestic US flight without ID in most cases.