This chart from GOOD.is compares the percentage of departing flights at major US airports that were either delayed or cancelled during the holiday season.
For instance, around 70% of the flights departing from Dallas Fort Worth Airport were delayed between December 26 and January 6 this year while that number was only 27% during the same period last year.
The flight delays can be attributed to increased security procedures as well as bad weather — US is facing one of the coldest winters since 1985.