Here in the Commonwealth, we write out dates in Day/Month/Year order, probably because it progresses in order of magnitude.
Why does the US do it Month/Day/Year? Is it just to be contrary?
Because Americans typically say “November 24th”, whereas we usually say “the 24th of November”.
No. Sometime centuries ago, it became more common in speech to say “September twelfth (1973)” rather than “the twelfth of September (1973).” The written form simply followed suit.
That “No” in my post was in repsonse to the OP question about being contrary.
As an American wanting to be contrary, since at least 1997 I have been following the notation set forth in ISO 8601, which recommends YYYY-MM-DD for shorthand dates. I switched for many of the same reasons put forth in the linked page, well before I was even aware that an international standards body had recommended that notation.
Are you guys sure? Because it seems to me both cultures use both ways.
I wasn’t aware that Australia used DDMMYYYY. That seems wrong from all logic.
The common US for MMDDYYYY is, indeed the direct quote from the normal spoken English.
The international standard (used most places I have seen) is YYYYMMDD because it directly computer sorts with minimal programming and confusion. You will find that even in the US, computer applications use this format if the programmers get their way.
Um what about days < months < years?
For real. Nobody would ever think of writing the time 11:05 as “5:11” no matter how frequently they said “five minutes past eleven”.
From normal spoken US English that is, in English speaking countries it is more common to say: “the 12th of September” than “September 12th”.
DDMMYYYY is the standard in Britain too.
And Canada, as usual, has a mixture that leads to all sorts of confusion as people use one system and have it interpreted as another. What makes this worse is the number of people who still use a two-digit year and write the date in all numbers.
I work for a company that spans North America, Europe, and Asia. I might get a copy of a memo with the date written 01/02/03. It’s been forwarded and copied from person to person and from office to office. Quick! When was the original message written?
My desk phone says 24-Nov-03. Payphones display 24/11/03. The newspaper is dated November 24, 2003. A printout from Shipping downstairs is dated 11/24/2003. The contents of the printout, a listing of tracking info for a package, is listed by date: 2003-11-24. In selfdefense, I write the name of the month: 11 Nov 2003–but I’ve occasionally seen the month written in roman numerals: 24 XI 2003.
I say we standardise all numerical dates in the 2003-11-24 format.
Really quite irrelevant on several grounds.
Uh… sorry?
In light of the several different systems in use, why pick on the American system as the “contrary” one?
From http://www.ojp.usdoj.gov/search97/doc/user/c_is2.htm
Month-day-year, American numeric date format.
Day-month-year, English numeric date format
Year-month-day, European numeric date format
Year-day-month, Swedish numeric date format
That aside, the better question would be, why did you Brits change from the system you established in America?
From http://en2.wikipedia.org/wiki/Calendar_date
11/16/2001 - used in places with American influence. This format was traditional in England, whence it was brought to America. Since the 1900s the English have begun to use the d/m/y format, imported from Europe.
And from http://www.raycomm.com/techwhirl/archives/0110/techwhirl-0110-00454.html
“Month, day, year” was perfectly acceptable British usage about two centuries ago…
So anyway, the answer to the OP question is, “Because that’s the tradition established here by British colonists centuries ago.”
I work for the Department of Defense. We habitually operate on both the 24-hour clock and on the DD-MMM-YYYY date format or something close to it. It drives most other Americans batty.
When you work on a military installation, you will get dirty looks, and people will make fun of your emails if you write the date like “November 24, 2003” It’s expected to be something like the following examples:
24 Nov 03
24 Nov 2003
24 November 2003
Of course, you can get away with just “24 Nov” or “24 November” if the year isn’t necessary. If you write the date numerically, it’s usually 11/24/03, but the preferred numerical method on many forms is 20031124. But, in correspondence, you don’t write the date numerically. You put down “6 Dec” and you look cool.
And of course, it’s currently 1600, not 4:00 pm. But that’s a different thread.
All this has crept into my own personal habits. I date my checks “24 Nov 03,” and my wife thinks I’m nuts.
Someone must have lied to you. Sweden uses YYYYMMDD.
In Hungary, it’s customary also to go Year-Month-Day, and not just in numeric format. For example:
2003 julius 12
Hey, don’t you date/month/year folks also drive on the left side of the road…? 
Which Europeans do this?
It seems to me that the date of the month is the one perhaps most likely to be questioned, as, well, it changes faster. I mean people might look up from writing and ask - “oh, what’s today’s date”, when the chances are they know the month but need to check the date of the month. Then the month, of course, changes more quickly than the year does. So in terms of what is likely to be debatable at all, or need cheching at all, there is a logic in the order of DD MM YY (or YYYY).
OK I do get confused about years too, but, only till about, um, February. 