Pent-up travel demand caused by the restrictions put in place to combat the spread of COVID-19 has resulted in a spike in 2021 bookings for airlines.

According to The Associated Press , the Transportation Security Administration (TSA) screened more than one million people at airports across the United States on Sunday, marking the 18th straight day of reaching the milestone.

While Sunday’s total number of screened passengers was still down 37 compared to 2019, TSA officials told The AP the milestone is “easily the most prolonged travel rebound during the pandemic.”

On Monday, Bank of America said the recovery of leisure travel is in full swing despite new restrictions in parts of Europe and continued warnings against non-essential travel from the U.S. Centers for Disease Prevention and Control (CDC).

American Airlines also announced Monday bookings were beginning to approach pre-pandemic levels due to the rising number of vaccinated Americans, reaching 90 percent of bookings during the same period in 2019.

The carrier said travel demand is strongest for domestic and short-haul international trips .

Other airlines such as Delta and Southwest have also reported a spike in bookings that started around mid-February .