Exhausted travelers sought passage by other means using different airlines, rental cars, or trains — or they've simply given up.

According to the FlightAware tracking service, more than 91% of all canceled flights in the U.S. early Wednesday were from Southwest, which has been unable to recover from ferocious winter storms that raked large swaths of the country over the weekend.

The operational systems of Southwest have been uniquely effected, so much so that the federal government is now investigating what happened at the Dallas carrier, which has frustrated its own flight and ground crews as well.

This week, with cancellations from other major airlines ranging from none to 2%, Southwest has canceled nearly 10,000 flights as of Wednesday and warned of thousands more Thursday and Friday, according to FlightAware.