I have an American green card and want to travel to Cuba from the United States. If I go from Canada, how can I leave no trace and not let the United States know that I have been to Cuba?

The exit record is not registered on the American green card, but on the passport. If it is not easy to check, it is a green card for going to Canada, a China passport visa for going to Cuba, and a new passport when you come back. In this way, there is no record of going to Cuba on the surface of the new passport, but there is still a computer record. If you want to be naturalized, you will definitely check the detailed computer records, not just the stamp on your passport; Once you are found hiding, it is a direct refusal. If you ask stowaways to get you a passport, you won't find it with this passport. China needs a visa to go to any country for a private passport (that is, a personal passport), but few countries can go to landing visa.