When I go to america can I use my iPhone 4S but with an American SIM card?

If I use a cheap sim card will it still work? Where would I buy it and get credit?

Yes it will still work if the device is unlocked and if you go into tmobile or ee and make sure you get a tmobile i'm you wll get fleible booters wich alow you to use it in other coutrie for free

Yes i'm a business women and travelling to America with my iphone 4s is simple just get a cheap US simcard and use it for you duration. I bought mine from a corner shop and it was less than 1 dollar.