A new study reveals Delta and United Airlines' major hubs dominate the list of most unreliable U.S. short-haul flights by cancellation rate.

United's major hub had a difficult start to the July 4 holiday weekend, with hundreds of cancellations and delays, as well as diverted flights.

United Airlines and other carriers continue to pivot as the partial government shutdown drags on. Hubs are now using ICE agents at security checks to help the lines flow more quickly. As of now, lines ...