Citing strong summer travel demand, United Airlines is adding hundreds of flights back to its July schedule, and is adding or resuming dozens of flights at its two biggest hubs in Chicago and Dulles.

United is adding more than 400 daily flights to its July schedule, including increasing service to reopened European destinations. The company said it will be flying 80% of its U.S. schedule compared to July 2019, and that bookings for summer travel are up 214% compared to 2020 levels.

At Dulles International Airport in Virginia, United will increase daily departures to 220 flights. That includes new service to Athens starting this July, and a second flight to Frankfurt.

“As we start to see strong desire from our customers to travel internationally to reopened countries, we are excited to move up service,” said Patrick Quayle, vice president of United’s international network.

United is the dominant carrier operating at Dulles.

The Transportation Security Administration screened 1.86 million passengers at U.S. airports on May 16, the single busiest day at U.S. airports for travel since the onset of the pandemic. That compares to 2.6 million passengers the same Sunday in May 2019.