 The summer travel boom reached a new record high Sunday. The TSA says for the first time, more than 3 million people pass through its airport security checkpoints in a single day. Experts say cheaper airfares and a stronger U.S. dollar are motivating Americans to fly and helping their vacation money go further. The results? Nine of the ten busiest air travel days in the TSA's history have occurred since Memorial Day weekend. Goodness gracious. Busy. Man, those cheaper airfares though, just kind of wondering where they are.