The U.S. airline industry was born in subsidy from the post office and American Airlines received a federal loan to pay for its first big aircraft order. The U.S. airline industry has more government involvement than most countries — the U.S. model where airports are owned and run by government agencies, and air traffic control is managed by the government is unusual.
Big U.S. airlines like Delta, American, and United have all benefited from major government subsidies, like moving pension obligations off their books and onto the federal Pension Benefit Guaranty Corporation in bankruptcy while retaining tax loss carry forwards so that they wouldn’t have to pay taxes once they started earning profits.