Guess the English name of the country, based on its name in Esperanto. If you didn't know, Esperanto is the most widely spoken constructed international auxiliary language.
According to Duolingo, Usono is the United States. The Wikipedia article for the US is under Usono, though it agrees that the official name is Unuiĝintaj Ŝtatoj de Ameriko.
The country "United States of America" in Esperanto is "Usono", if you put "Unuiĝintaj Ŝtatoj de Ameriko" it's like putting "Republiko de Barato" instead of "Barato"