One of the minor mysteries of life is why people insist upon referring to the country known properly (but misleadingly1) as the "United States of America" as either "America" (which name really applies to the entire New World; this is why the continents in the Western Hemisphere are called North and South America) or the "United States" (of what: Mexico? Brazil?). Why not just call it the "USA," which is quicker to say anyway than either "America" or "United States?" To do so would certainly be more consistent with our practice of devising a stupid abbreviation for any commonly-employed word that comprises more than two syllables, e.g., "carb" for "carbohydrate," e-mail" for "electronic mail."
Another problem with "United States," as well as with the full name, is that no adjective can be derived from it, as "Canadian" has been from "Canada." Of course, we refer to ourselves as "American," but, again, anyone living in the Western Hemisphere qualifies for this designation; I've heard that people in such places as Argentina often call themselves "Americans," and resent our presumption that we have an exclusive claim on the title. A less-commonly used term for this country is "Yankeedom," but even this would be regarded as offensive by Southerners. I know of no current option preferable to the facetious one in my comic strip Wild Life, which is to pronounce "USA" as if it were a normal word rather than to spell out the letters of the acronym, and to derive from it (by analogy with the word "ufology") the adjective or noun "Usan." Another quandary solved by cartoon characters!
1 A "state" is by definition a sovereign political unit, hence such words as "statesmanship"; it's a misnomer when used for such a place as Connecticut, which has so little independence of action these days as to be hardly more than a satrapy of an empire governed from the District of Columbia.
