NEW YORK - Residents of the US Northeast were digging out of snow Tuesday after the worst of a brutal holiday-week blizzard having passed Monday afternoon but with the headaches remaining for tens of thousands of stranded airline passengers. By Monday evening, planes had begun landing at Kennedy and LaGuardia airports, two of New Yorks airports in an effort to clear the backlog of passengers, waiting in airport terminals for more than 24 hours. This storm was one of the most challenging storms weve had in a decade or two, New Yorks LaGuardia Airport General Manager Thomas Bosco said. We had 25 inches several years ago, but the snow stayed in place. Today the snow piles are drifting. Countless cold, hungry and tired passengers were hunkered down in airports, train stations and bus depots. Some were given cots and blankets. Others used their luggage as pillows, curled into chairs, or made beds by spreading towels on the floor or overturning the plastic bins used for sending items through airport security. Some airline passengers could be stuck for days. Many planes are booked solid because of the busy holiday season, and airlines are operating fewer flights because of the economic downturn. As bad as the storm was, it could have been worse if it had been an ordinary work day. Children are home from school all week on Christmas vacation, and lots of people had taken off from work. Many youngsters went out and frolicked in the snow, some of them using the sleds. The storm was New York Citys sixth worst since 1869, when records began, according to a meteorologist with the National Weather Service. New Yorks Mayor Michael Bloomberg defended the citys response to the storm as competent and sufficient on Monday. The world has not come to an end, he said. The citys going on. Many people are taking the day off. Most stores are open. Theres no reason for anybody to panic. The Sanitation Department said most of the citys major avenues had been cleared, but side streets remained a challenge in part because of stranded cars. City officials say they dont expect New Yorks mass transit to be operating normally on Tuesday, though hopefully most of the streets will be cleared. On balance I think youll find we kept the city safe and were cleaning it up, Bloomberg said.