Reasoning for American date format

Question

In America the date format is mm/dd/yyyy but in Europe its written dd/mm/yyyy, what is the reasoning behind the American format, surely the most used piece of info in that string is dd so why put forward the month first ?

Answer 1

It seems it is just convention, as you can also see at this discussion. The American format follows the phrase "November fifth", while the European one follows "the fifth of November".

When designing an interface you might find useful having fields with the name of the month, like 05 - Nov - 2013 or Nov - 05 -2013 instead of using numbers and guidelines/explanations of the format you are using.

Answer 2

While your question is valid, your underlying assumptions are not.

surely the most used piece of info in that string is dd

Really? The question of what part of the date a user might be interested in, is really not all that easy to answer. It really depends on the application. Sometimes the day might be most relevant, but for other purposes the month, year or even century might be what the user is looking for.

Iso format

If you're looking for a really rational way to format dates, you should look at the ISO format yyyy mm dd (the spacing is optional, really). In this format, you put the most significant (as in: largest contribution to the total value) piece of information first, just like you do with every other number. Benefits include that this format sorts naturally in chronological order.