What city is USA?

Excuse me, but I must inquire about the statement you've just made. It seems there might be a misunderstanding. When you ask, "What city is USA?", I'm assuming you're trying to inquire about the geographical location or a specific place within the United States of America, which is a country, not a city. Could you perhaps clarify your question? Are you looking for the capital city of the USA, which is Washington D.C., or perhaps you're interested in learning about one of the many vibrant cities that make up this diverse nation?