WEBIl y a 3 jours · Officially: United States of America. Abbreviated: U.S. or U.S.A. Byname: America. Head Of State And Government: President: Joe Biden. Capital: Washington, D.C. Population: 331,449,281; (2024 est.) 341,963,000 2. Currency Exchange Rate: 1 US dollar equals 0.937 euro. Form Of Government: