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?

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    I think if you are writing an essay you should rather use "United States" or "United States of America" rather than abbreviating.
    – major-mann
    Mar 21, 2014 at 20:40
  • I suspect that if you scanned this board you would find that "US" (without periods) is by far the most common representation. But, of course, most writing here is somewhat informal.
    – Hot Licks
    Jan 20, 2016 at 22:51

5 Answers 5


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. ...

  1. 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).

  2. 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.

  • Good answer. But I hate it. It speaks a very sad truth that I don't want to deal with. Mar 22, 2014 at 2:52
  • @Spike: What sad truth?
    – 3Doubloons
    Mar 22, 2014 at 4:02
  • We like to think that we're smart, but we can't really decide on whether or not to use a period or two. Throughout School they teach us to use periods in between U.S, for example, and give us low marks if we forget. But in recent years I've noticed more and more people not using periods at all, and not even bothering to capitalize abbreviations, and even failing to use punctuation. There's a reason they were used in the first place, why can't we just stick to it? It made sense then, and nothing has really changed, so why doesn't it still make sense? Mar 22, 2014 at 4:57
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    @deletethisaccount Well, the reality is that language has fashion just as clothes do - how one writes, how dots and slashes are used, is inextricably tied to our life experience and the time in which we live and were raised. Your preference to do as you were taught in school, for instance, is a good example of this. Fashion is not set in time, and what was judged as refined in clothing might now be seen as worn, tired, or unnecessarily formal and thus out of place. Sadness is the result when we try to treat something impermanent as though it were eternal. It helps to think: it's just a dot...
    – BrianH
    Oct 21, 2014 at 14:42
  • Indeed, @BrianDHall. Most punctuation, a great deal of spelling, and most of what was traditionally taught in schools as grammar, are all fashion.
    – Colin Fine
    May 12, 2016 at 22:53

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.


  • 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).

  • It may be worth distinguishing between U.S./U.S.A. as a noun and as an adjective. According to Garner's Modern American Usage: "'U.S' is best reserved for use as an adjective {U.S. foreign policy}, although its use as a noun in headlines is common." I don't know if I agree with his advice (U.S. as a noun seems fairly natural to me) but the distinction is something that your relative frequencies wouldn't necessarily reveal, and POTUS is the only one of your examples where it's used as a noun.
    – Curtis H.
    Mar 21, 2014 at 17:10
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    @CurtisH. That's a good point. However, as you say, I think it's fairly natural to use the term "U.S." as a noun. There are a number of examples e.g. in today's Wall Street Journal.
    – AM55
    Mar 21, 2014 at 17:13
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    Regarding talking to people in Venezuela, Cuba, or elsewhere in South/Latin America, I would actually say it's better to use "US". In most Spanish dialects it's called "los Estados Unidos" (the United States) and citizens of the US are called "estadounidense" (literally, United-Statesian). The use of "America" or "americano" are often offensive because it implies the US is the only part of the two American continents that matters. Mar 21, 2014 at 21:14
  • The Google search term "US" also returns results for the word "us" meaning "you and me" so I'm not sure that these results are correct. In Google search, placing the search term in quotes does not capture the letter case of the word.
    – Davbog
    Mar 15, 2019 at 19:51

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.

  • Very true. HERE in India, USA is used more formally and US is used mainly by Indians having relatives living in the USA! May 22, 2017 at 6:33

For most usage in English, the abbreviations are identical. The United States of America is the only country on either continent with "America" as the only distinctive proper part of its name, and certainly the only English-speaking country commonly called that.

Within a given work, however, it's far more important to be consistent than to be correct. The practice for legal documents is to parenthetically note the abbreviation or pronoun you use after its first instance, and then use such throughout. For a simple essay you can skip the notation of a common abbreviation, so long as it's not confusing.


The United States of America is made up of several states. Some of these, like Michigan (MI) and Mississippi (MS) have very similar abbreviations. It's not uncommon even for those familiar with the USA to be unsure if MI or MS is the one with Detroit or the one with Mardi Gras.


I know this old but I'm sure someone else could use the answer later. We are told ignorance of the law is no excuse by the same people trying to hide the facts and make it as difficult as possible for us to understand. This will help anyone who needs it.

There is a difference. The "United States" refers to the Federal government, whilst the "United States of America" refers to the 50 States of the Union.

The legal definition for the United States of America; "The United States of America are a corporation endowed with the capacity to sue and be sued, to convey and receive property."

Courts have opined (3) legal meanings for the term "United States."

"The term "United States" may be used in any one of several senses. It may be merely the name of a sovereign occupying the position analogous to that of other sovereigns in the family of nations. It may designate the territory over which the sovereignty to the United States [672] extends, or it may be the collective name of the states which are united by and under the Constitution."

None confirmed or legitimized by an act of Congress.

Furthermore, The United States of America is incorporated as 3 different Corporations. Twice in Delaware and once in Scotland.

The United States of America, Inc. and United States of America, Corp. are incorporated in Delaware.

The United States of America, Ltd. is a Limited Corp. incorporated in Scotland. The registration is held at White House #2 (sister White House) in Edinburgh. The country of origin for USA, ltd is U.K., which in my opinion confirms what I've suspected for a long time, we are still owned by Britain. (see original American flag "Grand Union Flag"). But that's a complicated story.

In short, wording is very important in regards to US law. Simple things like "are" or "is" can render an accepted perception of a meaning false. It's obvious Legislation intentionally creates vague and ambiguous terms to allow Courts headroom to conform the laws as needed, or rather desired (if law was all that mattered then legal meanings/definitions wouldn't vary by jurisdiction)

Some think the "United States" is a federal corporation, mainly because of Title 28 3002, which states, (15) United States means (A) a Federal corporation;

But that's specific only to that Chapter, not as an encompassing definition. The federal government has never been a federal corporation, plus the Supreme Court barred Congress from re-defining any terms used in the federal constitution anyway. But it should be amended for the unconstitutional nature as it stands now.

I know it seems overwhelming and complicated and if anyone rather just do simple I can't blame them. But if truth matters then the best way to research this (or similar) is by just starting with the knowledge of following facts;

There are (2) United States (US / USA), (2) Constitutions (the constitution / this Constitution), and (3) Presidential Offices (Office of President / President of the United States / President of the United States of America)

The actual "Office of President" has never been filled by anyone. The reason being, the Constitutional oaths are controlling factors of office.

Put simply, which oath 1 takes decides what office they fill. The oath taken by the 9th President, George Washington (only 1st under Constitutional scheme), was under Article II, (President of the United States), not (Office of President) which requires oath under Article VI. All Presidents have followed the same suit since.

That scheme against the people is why the Constitution was drafted in secret. (also why Washington was nervous taking oath) He knew he could likely be killed if caught. Patrick Henry's "I smell rat" was for good reason, yet he was ridiculed. But indeed he did. Same rat out of control today.

Whether anyone sees it or not, this info goes directly to the heart of the matter, the U.S. separated from U.S.A.. But once you dive in you'll see how quickly the pieces fall together and the dots start connecting.

You'll start to see the reason for all this trickery & deceit and what it basically comes down to. 1 giant ass tax & property theft scheme by the governments usurping of powers.

We're all just citizens subjected to a treasonous scheme and criminal trespass under guise & color of law.

America wasn't built, it merely spread.
-Cairo Anubiss (American Composer)

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