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Why is the most common date format in the US like mm/dd/yyyy, whereas in Europe (including the UK) it's more common to have dd/mm/yyyy?

Looking around, I found that the US form is actually the more traditional Anglo-Saxon way, but the British adapted to using the European form in the early 20th Century.

But I couldn't find a definitive discussion of the history of the different formats. Is it just conventional, or is there an official 'British date standard' (like with metric and imperial, for example).

share|improve this question
There are no "rules" -- but there is rigidly enforced convention in order that everyone knows what everyone else is talking about. Not quite sure whether this counts as ELU or not, though. – Andrew Leach May 24 '12 at 12:00
Vaguely related: How to write out dates correctly – Matt E. Эллен May 24 '12 at 12:27
Anglo-Saxon (i.e. English ca. 500-1100 AD) dates were written in full sentences (e.g. "fifteenth day before the calends of April" -- Anglo-Saxon Chronicle) rather than using any kind of notation. At least, that's been my experience. Is that what you really meant to say? – arcresu May 24 '12 at 16:20
I think it depends on the context. In the UK, for example, for "information interchange" something similar to ISO8601 is ratified as BS ISO 8601:2004, BS EN 28601 standards (which are preferred). So the format yyyy-mm-dd became pretty common on official documents, manufacturing stuff or interfaces. – Tiberiu-Ionuț Stan Apr 11 '13 at 0:23
I have no sources to quote as such, but personally prefer to use a logical format starting with the lowest unit (days) and ending with the highest (years), thus the 4th of July would be most logical (to me anyway) in European format as 04/07/13, not 07/04/13. – user42857 Apr 19 '13 at 23:36

Ask a simple question, get a simple answer: it’s because that’s how we speak it in English:

Today is Thursday, May 24th, 2012.

Now convert the month name to a natural number, and there you have your answer. What’s today’s date? It’s May 24th. Instead of writing May-24, we simply change the “May” to “5” and write 5-24 or ⁵⁄₂₄.

That way it follows the natural language order and so requires no mental gymnastics to switch things around when speaking the date aloud. Similarly “September 11th” gets written ⁹⁄₁₁, etc.

The full spoken form with the year, “May 24th, 2012”, then becomes the written shorthand “5/24/2012”, or often just “5/24/12”. “Christmas of 2001” can be, and somewhat annoying often is, written “12/25/1”, while “January 25th, 2012” becomes “1/25/12”.

This isn’t usually any sort of problem because of universal consensus on how to interpret such things in the United States. If you write day/month/year in America, you will not be understood. Although I myself prefer the ISO notation, normal people do not use it in their daily affairs.


I’ve deleted the rest of the material in case it was distracting the downvoters. I have no idea what the downvoters are disagreeing with, since they did not condescend to say why. The standard and accepted answer as to why Americans write the month first is indeed because they say it first in speech. A trivial Google comes up with this very same answer repeated dozens and dozens of times.

I suggest that if you do not like this answer, you do me the courtesy to say why you think this one is wrong. Even better, provide your own answer if you think mine is wrong.

share|improve this answer
I don't speak it that way. I say "Thursday the 24th of May" but then I'm British. – Andrew Leach May 24 '12 at 12:53
Fortunately we all have our own culture-specific Date::Format routines :-) – Andrew Leach May 24 '12 at 13:02
So are you saying Americans would never say the "Fourth of July"? :) One way became popularized in one part of the world, another in another, and yet another in yet another. Once a pattern became popular in print and conversation, it was likely to reinforce itself. – choster May 24 '12 at 15:08
Re your edit, I didn't downvote (or upvote) but the problems may include the following. You say US order follows the 'natural language order' but I don't think that makes sense as those of us in other countries find the DMY order natural. You say that the US format is because people (in the US?) talk like that, but how do you know it's not that people in the US talk like that because that's the official date format? If the latter then you haven't answered the question. You say there are plenty of references on the web, perhaps you could provide links to the more persuasive ones? – Gaston Ümlaut May 25 '12 at 1:36
Because of the ambiguity that arises for the first 12 days of every month, I prefer either yyyy/mm/dd or dd/mm/yyyy so that one is either getting more or less specific as one goes along, not jumping from month to day to year. Being in the computer industry, I really prefer yyyy/mm/dd because it alphabetizes better. – TecBrat Jun 4 '12 at 4:02

Personally if I was to say a date I would do so in the format mentioned by Andrew Leach, or even 'the 24th of May'. I suppose it depends on what you're used to. The American date format often has me confused unless the month is spelled out.

share|improve this answer
In America, we would say If I were to say a date... :) – tchrist May 24 '12 at 15:08
I think you should only use were in this context if it is contrary to the fact. For example 'if I were you' as opposed to 'if I was you'. – Alex May 24 '12 at 19:55
But “If I were you” is contrary to fact; that’s why the “then” takes “would”. These are non-hypotheticals: ❶“If he really did drop it by yesterday, then he didn’t have it with him today.” ❷“If I was distracted, then she was absolutely captivated.” ❸“If he dropped it by, then it’s around here somewhere.” ❹“If he was here already, you really must take this back with you.” See? No “would” in 2ⁿᵈ clause! But these are hypothetical: ⓵“If I were you, I wouldn’t say that.” ⓶“If he’d had it with him, he would have given it to me.” There are many others I’ve no space to write here. – tchrist May 24 '12 at 20:19
I agree with you that using were is correct if the subjunctive is contrary to the fact, as furnished by the example 'if I were you', however the sentence '..if I was to say a date I would do so in the format...' does not contain anything to the contrary, hence was is acceptable. – Alex May 24 '12 at 20:45
@tchrist This is not relevant to the question and should be taken to chat. Anyway, what's your data to show that native English speakers don't use 'was' in that way? – Gaston Ümlaut May 25 '12 at 1:40

It's very possible that the US inherited this from an outdated English format - much like the length unit, after Henry III's foot and which the English have left behind in favour of the more logical metric system.

One argument I've heard in favour of the American system of dating is that the numbers of months in a year is smaller than the number of days in a month which itself is smaller than the number of possible years. So you would have 12/31/2013, in ascending order. I don't really buy this argument, but OP might be interested in it anyway so here it is.

Meanwhile, in Northern Europe they've moved on to an opposite, descending date standard: year/month/day.

share|improve this answer
That’s simply ISO 8601 format that uses YYYY-MM-DD. The rest of your diatribe against the traditional English measurement system is simply misplaced bigotry and has no place here. – tchrist Jul 5 '13 at 18:27
I argue that it's very relevant, if the US preserved various systems used in England before it achieved its independence. But ok? – Corina Jul 5 '13 at 18:32
@tchrist: It didn't read as a diatribe or as bigoted to me. It was one sentence, with one concrete example (the foot), given to corroborate the plausibility of borrowing from the English. The closest thing to a "value judgment" in the whole thing is that the metric system is more logical than the old English (and current American) system. But the thing to that is, I don't even see Americans ever argue that feet/inches/miles/etc. are more logical than the metric system. Honestly, that judgment isn't in serious dispute, anywhere. – John Y Jul 5 '13 at 18:54

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