American travel issues such as duty-free shop shopping during the flight from Shanghai to Dulles, San Francisco.

After you enter San Francisco, you transfer to a domestic flight. There are no duty-free shops. Now that we have entered the country, we certainly don't go to the duty-free shop to buy things. Besides, the entry allowance for non-American citizens or permanent residents is only $200, so don't worry! As for your return trip, it's the same. There are no duty-free flights in the United States. You only have a connecting flight in San Francisco for more than an hour, so the time for catching the plane is pressing. Do you still want to go shopping? ! On the surface, duty-free shops have not increased taxes, but the operating costs of airports are high, so they may not all be cheap, just to make up for people's greed and cheapness. If you have time to stroll around, you really don't have to struggle if you don't have time.