How did America and the American flag get their name?

Answer 1

Through explorer Amerigo Vespucci. He made a map of the whole continent, and later on, a German cartographer took his maps and used his name to signify the entire continent.

Later, as the New World was colonizes by Europeans, the term "The Americas" came into use to describe the two new continents. This usage led the British to begin referring to their colonies in North America as "The American Colonies", which is what the residents of these colonies also used self-referentially. Upon gaining independence, the former colonists settled on a very self-descriptive name for their new country: "the United States of America".

Linguists are not sure of when the switch in meaning took hold, but sometime in the early 19th century, the term "America" lost its old meaning in English, and instead became used as shorthand for the USA. In a similar shift, the term "American" lost its general meaning of anyone residing in the New World, and instead referred specifically to any of US nationality.

This is why modern usage of the term America and America refer specifically to the United States of America. In point of fact, no other nation uses the world "America" in its title (either formal or informal title). While several other languages and Demographics (particularly those of Central American origin) object to the use of America and American in solely a US-referential role, virtually all other languages use some word form of "America/American" in that meaning (though, it may not be the sole word meaning "US national" - e.g. Mexican Spanish uses "estadounidense" - literally, "national of the United States", and the word "america" may also retain the meaning of the whole continent(s) more in those languages than in English). Even in such languages, the trend seems to be to use the derivative of "America" more commonly than others - e.g. "americano" is now much more commonly used in Mexican Spanish than "estadounidense".

So, unless specifically used in a context where it obviously refers to the entire North and South American continents (e.g. the "Organization of American States", an international body), current-day usage of the word "America" or "American" in English refers to the United States.

In a similar manner, the term "American Flag" is an evolution from "Flag of the United States of America", and generally starts showing up in literature in the late 1790s, and seems to be in common usage by 1810 or thereabouts, generally replacing even "US Flag" by the mid-1800s.