A transit city for major American airlines in the United States.

United Airlines (UA) has three transit cities in the United States: San Francisco (SFO), Chicago (ORD) and Washington (IAD).

Delta Air Lines (DL) has two connecting cities in the United States: Seattle and Detroit.

American Airlines (AA) has only one connecting city in the United States, Chicago (ORD).

Of course, the above transit cities are only applicable to flights from Chinese mainland to the United States.