Thousands of flights are canceled or delayed one day after powerful storms swept across the eastern half of the country and disrupted thousands of others. The flight-tracking site FlightAware says more than 1,000 flights scheduled to fly into, out of or within the U.S. have been called off Tuesday, It says 4,200 others have been delayed. Travelers have been facing additional jams at airport security checkpoints as a partial government shutdown strains screener staffing. The disruptions come at an already challenging time for air travel, in part because the shutdown that began Feb. 14 has pressured staffing at some security checkpoints.