This is in European format, so November 4th to December 10th.

It's less a "European" format and more a "most of the world" format.

The only thing worse than mm-dd-yyyy is dd-mm-yyyy.

Long live yyyy-mm-dd

I have to disagree here. Both dd-mm-yyyy and yyyy-mm-dd are much much better than the mm-dd-yyyy. Both are very intuitive compared to the completely unintuitive mm-dd format.

"yyyy-mm-dd" and "dd-mm-yyyy" are both sorted - one descending, one ascendig.

"mm-dd-yyyy" is just an arbitrary bag of entities, and a part of the population memorizes the order of them.

It's not completely arbitrary, it matches the way we write out full dates or speak then aloud. January 2nd, 1900 becomes 1/2/1900.

Totally arbitrary. In French 2ème Janvier 1900 would be the most common.

I mean, it's no more arbitrary than any other order. In the context of "why does American English use this ordering", it has the desirable characteristic that it matches how we express dates in our everyday language. A trade-off exists between that characteristic and the desire to have the date go from smallest to largest or vice versa, but both approaches have practical benefits.

That is also arbitrary.

yyyy-mm-dd for the win indeed, if only for being naively sortable.

Yyyy-mm-dd is not used in real life because it puts the (in most contexts) least useful information first.

FYI: this is the common way to write dates in Sweden.

ISO 8601 also allows --mm-dd.

I use it all the time.

At least for the next 7979 years.

Confusingly to Americans, this is probably Nov 4th to Dec 10th, 2020.