The last day of the year-end holiday travel rush unfolded like since  for airline passengers: chaotic.

Airlines canceled more than 2,700 Sunday flights across the country and into and out of the United States, according to flight tracker . That’s on top of more than 2,700 Saturday flight cancellations, bringing the total since Christmas Eve to more than 15,000 canceled flights. This weekend’s cancellations marked the worst two-day stretch of the holiday travel season and affected passengers on nearly every U.S. airline.

The travel trouble is continuing Monday amid an , with more than 1,800 U.S. flights canceled as 7 a.m. Monday, according to FlightAware. Southwest Airlines has canceled more than 400 Monday flights, or 12% of its scheduled flights, JetBlue 136 flights, or 13% of its flights.