The Denver International Airport served nearly 25 million passengers in the first half of 2021 – a 55% increase from the first half of 2020, according to a passenger traffic data report released Friday.

The airport has had one of the most successful passenger traffic recoveries since the beginning of the COVID-19 pandemic, the report said. However, compared to the first half of 2019 before the pandemic, passenger traffic is still down 25%.

“The acceleration of (DIA)’s recovery in the first half of the year is welcome news after the steep decline in passenger traffic in 2020,” said DIA CEO Phil Washington. “We will continue to focus on our recovery and planning for the future so (DIA) can remain the state’s primary economic engine.”

Washington said the airport has been able to keep costs down for its airlines during the pandemic, resulting in the addition of new routes and airlines over the last year.

In last two months, the airport added Southern Airways Express and Air France as partner airlines. In the first half of 2021, the airport ranked as the largest station for Frontier, Southwest and United Airlines, according to the report.

In addition, in the first quarter of 2021, DIA had the second-largest domestic travel demand of U.S. airports – up from fourth-largest in 2019. This year, connecting passengers made up 42.3% of the airport’s total passengers, a nearly seven-point increase from 2019, data shows.

The airport added four domestic destinations this year with plans to add another two in the coming months. These will replace six domestic destinations DIA lost during the pandemic, according to the report. DIA’s current domestic network includes nonstop flights to 183 destinations in 45 states.

International travel at the airport has seen less recovery, with international passenger traffic up less than 3% from 2020 and down 54% from 2019, data shows. However, Aeromexico, Frontier and Volaris served more international passengers at DIA in the first half of 2021 than in the first half of 2019.

Since April, 17 international routes have been restored at DIA and five others intend to begin again soon, according to the report.