 Airports are crowded. Today is expected to be the busiest day in history at U.S. airports. AAA says the top destinations over the 4th of July period are Seattle, Orlando, and Anchorage. The travel website Hopper says the busiest airports are Atlanta, Dallas, and Denver, which makes sense since those are the big hubs for Delta, American, and United. Alex Stone, ABC News. The TSA says today some 3 million passengers will pass through security checkpoints. You're listening to ABC News. This show is sponsored by BetterHelp.