 Karen Travers, ABC News, Washington. The Transportation Security Administration is predicting that today could be the busiest travel day of the year as Americans head out early for the 4th of July holiday. The 53,677 commercial, cargo, and charter flights expected in the air today will be a one-day record for this year, but it won't stand for long. The Transportation Security Administration expects to screen over 3 million people tomorrow, the peak day during the Independence Day holiday, which runs through July 8.