What does the U.S. ticket tax apply to?

The U.S. ticket tax applies specifically to airline tickets purchased in the U.S. for travel within designated areas, such as domestic flights and certain connected flights that start and end within the U.S. This tax is part of the government's effort to generate revenue from air travel, and it distinguishes between international and domestic travel.

For international flights or tickets purchased for travel originating from outside the U.S., different taxation rules apply, often dictated by the country of origin or the ticket's destination. Additionally, airline tickets purchased globally do not fall under the U.S. tax jurisdiction in the same way since they are not issued within the U.S. territory. The mention of train tickets highlights that they are not subjected to the aviation ticket tax, as it specifically pertains to air travel and not other forms of transportation. Therefore, the correct answer identifies the specific context in which the U.S. ticket tax is relevant.