'the USA' vs. 'the US'
I am writing an essay where I need to make a reference to the United States of America. Often I hear this shortened to the US, but sometimes people also say the USA. Are there any difference between the use of the two? Is one more formal or correct than the other?
As a random example of what I want to write is Is the US the most beautiful country in the world?
Solution 1:
Here is an interesting discussion of US versus U.S. versus USA versus U.S.A. from Wikipedia: Manual of Style:
In American and Canadian English, U.S. (with periods) is the dominant abbreviation for United States. US (without periods) is more common in most other national forms of English. Some major American guides to style, such as The Chicago Manual of Style (16th ed.), now deprecate U.S. and prefer US. Use of periods for abbreviations and acronyms should be consistent within any given article, and congruent with the variety of English used by that article. In longer abbreviations (three letters or more) incorporating the country's initials (USN, USAF), do not use periods. When the United States is mentioned with one or more other countries in the same sentence, U.S. or US may be too informal, especially at the first mention or as a noun instead of an adjective (France and the United States, not France and the U.S.). Do not use the spaced U. S., nor the archaic U.S. of A., except when quoting. Do not use U.S.A. or USA, except in a quotation or as part of a proper name (Team USA), as these abbreviations are also used for United States Army and other names.
The Chicago Manual of Style, 15th Edition (2003) comes out strongly in favor of spelling out United States (rather than abbreviating it) when the term is used as a noun and not an adjective:
15.34 "U.S." or "US." Except in scientific style, U.S. traditionally appears with periods. Periods may nonetheless be omitted in most contexts, Writers and editors need to weight tradition against consistency. In running text, the abbreviation (in either form) is permissible when used as an adjective, but United States as a noun should be spelled out.
Words Into Type, Third Edition (1974) takes an even stronger anti-abbreviation position:
In the most formal writing, United States should always be spelled out; in other works U.S. is gaining currency as an adjective when preceding a government agency, department or organization or the name of a government vessel. [Examples omitted.] When used as an adjective with general terms, United States should be spelled out. [Examples omitted.]
Both Chicago and Words Into Type have so little regard for USA that they don't even mention it as an option in their discussions of abbreviations for countries.
The Associated Press Stylebook (2006), however, accepts both U.S. and USA as nouns, and seemingly views them as equally valid designations:
U.S. The abbreviation is acceptable as a noun or adjective for Unites States.
USA No periods in the abbreviated form for United States of America.
Nevertheless, I have never seen a style guide that approved of using USA as an adjective.
Update (June 23, 2017): More on 'U.S.' vs. 'US'
Having belatedly acquired the 16th edition of the Chicago Manual of Style (2010), I should note that it has substantially altered its views on the use of U.S. versus US from what they were seven years earlier (see above). The updated advice appears in three sections:
10.4 Periods with abbreviations. ...
Use no periods with abbreviations that appear in full capitals, whether two letters or more and even if lowercase letters appear within the abbreviation: VP, CEO, MA, MD, PhD, UK, US, NY, IL (but see rule 4).
In publications using traditional state abbreviations, use periods to abbreviate United States and its states and territories: U.S., N.Y., Ill. Note however, that Chicago recommends using the two-letter postal codes (and therefore US) wherever abbreviations are used; see 10.28.
...
10.28 US states and territories. In running text, the names of states, territories and possessions of the United States should always be spelled out when standing alone and preferably (except for DC) when following the name of a city: [example omitted]. In bibliographies, tabular matter, lists, and mailing addresses, they are usually abbreviated. In all such contexts, Chicago prefers the two-letter postal codes to the conventional abbreviations.
...
10.33 "US" versus United States. In running text, spell out United States as a noun; reserve US for the adjective form only (in which position the abbreviation is generally preferred.) See also 10.4.
So the current guideline seems to advocate using U.S. if you use "traditional" state abbreviations (like N.Y. and Ill.) but to use US if you use postal-code-style abbreviations (like NY and IL)—which Chicago now prefers. But there's no telling what the 17th edition will recommend when it appears in the next year or two. Recently a publisher at which I regularly do freelance editing switched to using US in running text whether the term is functioning as an adjective or as a noun.
Solution 2:
I would claim that the term "U.S." is far more common than "U.S.A.", and is in fact how the U.S. Government refers to itself.
Consider:
The U.S. Department of State (http://www.state.gov/)
The U.S. Department of the Treasury (http://www.treasury.gov/Pages/default.aspx)
The U.S. Department of Commerce (http://www.commerce.gov/)
The U.S. Department of Defense (http://www.defense.gov/)
That the President is referred to as the President of the United States (POTUS) not "POTUSA" (which is apparently the name of a band). For an Atlantic article about the ascention of this anacronym to the everyday vocabulary of Washington and White House government workers and staff, see here: http://www.theatlantic.com/past/docs/issues/97oct/wordimp.htm
The phrase "U.S." / "US" (in quotes) has 4,390,000,000 results on Google [21-3-2014], whereas "U.S.A." / "USA" has only 792,000,000 results [21-3-2014].
David M's commented that Mexico is also a "United States", but consider that Mexico is also a "United States in America".
All of this being the case, your audience matters. For example, if you're giving a talk in Venezuela or Cuba, you might err on the side of directly saying "United States of America" to avoid the implication that "the U.S. is important enough that just writing U.S. is a sufficient descriptor" (regardless of whether or not this is the case).
Finally, consider how it would sound to refer to "Russia" as the "Russian Federation" (+ Crimea?). If not technically correct, "Russia" is by far more common and well-understood term. That said, the U.S. does not have anything akin to Russia's history, and there are certain ethnic implications if someone is "Russian" though this is not necessarily so if someone is "American" or "from the U.S.".
Let me add one more thing: the term "USA" seems, at least to me, to have patriotic overtones. Consider the phrase "Made in the USA" (16 million hits on Google [21-3-2014]) or the U.S.A.! chant (http://en.wikipedia.org/wiki/U-S-A!_(chant)). So this may be worth keeping in mind depending on your audience (I'd invite others to criticize this comment).
Solution 3:
I work as an editor on international journals, so am quite interested in this topic. I read that the full name of the country is "The United States of America" and that in 1777 the Articles of Confederation announced, "The Stile of this Confederacy shall be 'The United States of America'". In Europe, we therefore usually employ the abbreviation USA, limiting US (which we understand to be an informal styling) to adjectives, e.g. US Fish and Wildlife Service, US Army, US dollar. The term US will always logically have more Google hits than USA simply because of this adjectival use, but those outside of the USA tend to use USA rather than just US when referring to the country. The journals I work for avoid using periods or stops between letters of abbreviations - deemed unnecessary.