What’s the legal, correct name for the USA, or US, or America, or United States or United States of America, or whatever it’s called ?
The official name is the United States of America. The US is one abbreviation, as is USA; United States and America are both shortened phrases from the United States of America
The working endonym in official use in the English language is American. The United Nations officially uses the term American as an endonym referring to a person from the United States, and U.S. dependencies like American Samoa have the endonym for the same reason.
Most native English-speakers use “American” as their colloquial term for a person from the United States as well.
Some people, mostly non-native speakers, use “US-American” and other phrases like that because in many varieties of Spanish and Portuguese, Americano refers to any inhabitant of North or South America and is not the endonym for someone from the USA.
Ironically though, Mexico is officially Estados Unidos Mexicanos (United States of Mexico).
This is not the case in English, as Canadians do not identify as “American” and many would be offended if you called “American”.
Exonyms like “US-American” are not official, at least not in English, and are not used in official documents at the UN. They might be used in Spanish UN documents; I am not sure though.
In colloquial English usage, US generally refers to things having to do with larger stuff like citizenship, government, etc, while American refers to people, commercial products, and culture.
So… (#=awkward/marked, *=ungrammatical)
American cars
American people
American culture
American movies
American shoes
*US shoes
#/*US cars
*US people
#US culture
#/*US movies
US government
US military
US citizenship
US dollar
#American dollar
American citizenship (fine… for some reason)
#American military (just a bit awkward sounding)
#American government
The full, official name of the country is:
United States of America.
It is seen written as, the United States of America. There are two reasons why a lower case [the] proceeds the name in writing.
States is plural, and as such it must be proceeded or introduced by a definitive article such [the]. Take for example our neighbor to the north, Canada. They would not welcome you to The Canada… you would instead be welcomed to Canada. Canada is not plural.
The second reason for using a definitive article [the] when writing the United States of America, is that the name includes a geopolitical noun, America. Any time a geopolitical noun is included in the name of a country, it must be proceeded with a definitive article [the]. An example would be the United Kingdom. It is not plural, but it does include a geopolitical noun.
The only time [the] is capitalized proceeding United States of America is if [the] is the first word in the sentence, or if being used as a title.
In all other instances the United States of America is always proceeded with a lowercase [the] as is demonstrated in the Preamble to the Constitution of the United States of America.
“We the people of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.”
Consider the common abbreviations used for countries when determining the proper name.
United States of America [USA]
United Kingdom [UK]
Democratic Peoples Republic of Korea [DPRK]