CNN
 — 

Another day of harsh winter weather brought continued air travel misery across the United States on Thursday with hundreds of flights canceled and many more delayed by snow storms and plunging temperatures.

As of 7:00 a.m. ET, some 748 airplane departures had been scrapped and 724 delayed within the US, according to flight tracking site FlightAware. The schedule disruptions come a day after more than 1,700 flights were dropped and and 6,700 delayed.

Blizzards, snow dumps and ice have hit a huge swath of the western and northern US stretching from California to New York and New England, with much of the upper Midwest experiencing particularly heavy snowfalls. More than 60 million people were under winter weather alerts early Thursday.

Minneapolis-St. Paul International airport was the worst affected with 132 departures and 94 arrivals struck off. Over the border in Canada, Toronto’s Pearson International airport was showing 68 departure and 55 arrival cancellations. Delta was the worst affected carrier, accounting for 198 of overall cancellations and 107 delays.

Chicago O’Hare International, Boston Logan International, Portland International and Denver International were also showing significant impact.

On Wednesday, Southwest Airlines issued winter weather waivers for about a dozen airports. Delta Air Lines has issued waivers for Upper Midwest winter weather and Rockies and Mountain regions winter weather. American Airlines and United have also issued winter weather waivers for travel this week.