- Someone from los Estados Unidos is called <u>estadounidense</u>.
Explanation:
Though in the <em>US</em> is common mentioning the people how <em>American</em>, in <em>Latin America</em>, <em><u>is badly seen mentioning the people of a country how the people of all the continent</u></em>, by this reason, How United States of America is in Spanish "Estados Unidos de América" the correct demonym of a resident from the US is "estadounidense".