According to a new study commissioned by the U.S. Travel Association and performed by Oxford Economics, the United States owes $4.1 billion of its 2014 GDP to the 1.1 million visitors who flew into the country with Persian Gulf airlines Emirates, Etihad and Qatar Airways.

The study also found that the passengers brought to the country by the Gulf airlines—and the money those visitors spent here—helped support 50,000 American jobs that brought in $2.6 billion in income and more than $1.1 billion in tax revenue on the federal, state and local levels.

These Gulf airlines operate in the United States under the Open Skies treaties—a collection of free trade agreements for international passenger aviation routes. The Big Three domestic airlines (Delta, American and United) have put forth efforts to freeze two of the treaties, fearing that international airlines are being allowed to encroach on their customer bases. The study claims that only two routes operated by the Gulf airlines (in April 2015) were in direct competition with the Big Three, and that more than 82% of the Big Three’s passengers flying into the U.S. in 2014 originated in the Americas or Europe, while more than 80% of the Gulf airlines’ analogous passengers boarded in South Asia or the Middle East.

Furthermore, the study found that 56 percent of Gulf airline passengers arriving in the 2014 transferred onto a domestic airline to complete the journey, representing 620,000 travelers and $140 million in revenue for the domestic airlines.

So why would the Big Three U.S. airlines want to freeze agreements that would appear to benefit their industry and even their own bottom lines? We may have to wait until they commission a study of their own to learn the answer to that.

The full report from the Oxford Economics/U.S. Travel Association study, can be read here.