To which country does the man plan to travel?

M：You know I am flying from Shanghai to Pittsburgh.The thing is there is no direct flight and I’ll have a 10-hour layover at San Francisco Airport.Can I leave SFO as a transit passenger?I don’t want to be stuck in the terminal that long.I feel like touring around downtown San Francisco.
W：Yes,you can.Actually you are not a transit passenger in a strict sense.You have entered the United States and your connecting flight is just a domestic one.But you’ve got to go through the security check again once you’ve left the airport or changed the terminal.So leave yourself plenty of time and don’t miss the next flight.
M：Got it.So for me San Francisco is my port of entry and I’ll go through the US Immigration and Customs there?
W：Exactly.You’ll go through the Immigration right after you get off the plane.So get ready your passport,DS-2019 and prepare to answer some questions like the purpose of your visit,how long you will stay.
M：I then proceed to Baggage Claim to get back my hold luggage after I’ve cleared the Immigration?
W：Correct.
M：Is there any place at the airport to store my luggage?I can’t imagine walking in downtown San Francisco hauling two heavy suitcases.
W：Well,you can check in your luggage for the connecting flight immediately.Usually there are clear signs indicating where you should go for the connection check-in.
M：I have a carry-on.Can I put it on hold this time ’cos it’s still quite a hassle carrying it around?
W：Well you can,but you have to pay and it’s quite expensive.I remember last time I tried to do the same thing but they said it’d be at least 70 USD for one piece.