United Airlines is increasing service at Glacier Park International Airport this summer for three major markets.

Flights will be added for San Francisco, Chicago and Denver.

Beginning July 1, the airline will offer daily flights to San Francisco and continuing through Sept. 5. Seasonal flights to San Francisco are currently available once weekly on Saturdays through March 25.

In addition, United Airlines will begin using a larger Airbus 319 aircraft on existing direct flights to Chicago and Denver this summer. This will increase flight capacity by 17 percent to about 128 passengers to Denver and an 82 percent capacity increase to service to Chicago. The increased capacity will be between July 1 and Sept. 5.

The changes in flights follow record-breaking traveler counts at GPI in 2016.

Robert Ratkowski, Glacier Park International Airport’s director, said the decision to expand service is strongly tied to the tourism boom that the Flathead Valley, and specifically Glacier National Park, has experienced in recent years.

“United has been increasing capacity in our market since last summer,” he said. “They have seen double-digit passenger growth for the last five months, including almost 40 percent growth in September 2016 compared to September 2015 ... We appreciate that United is investing in our market. They are increasing competition and the potential benefits for our community are significant.”

The additional flight capacity will also benefit Flathead Valley residents trying to travel during the summer when flights are usually booked solid for weeks, Ratkowski noted.

Glacier Park International Airport experienced a surge in 2016 with nearly 500,000 travels using the airport, surpassing the previous record year, 2015, by almost 5 percent.

For more information, visit www.iflyglacier.com.