Thanksgiving will test whether airlines have done enough to insulate their operations from shocks that have roiled air travel in recent months.

The Transportation Security Administration said it expects Thanksgiving travel to come close to pre-pandemic levels, with 20 million people likely to pass through U.S. airports over a 10-day period. Airlines including Delta Air Lines Inc. and United Airlines Holdings Inc. said they expect the Sunday after Thanksgiving to be the busiest day since the start of the Covid-19 pandemic.