If you’re American and reading this post, you might be asking the question “why do Europeans put the date down wrong?” You might be thinking this because when writing down the date, Europeans will use the dd/mm/yyyy format. Americans (and maybe some Canadians) will be more familiar with the mm/dd/yyyy format. It’s a distinction that gets confusing any time the day in the month is less than 12. Unfortunately for you, it’s actually Americans that are wrong—if your metric for correctness is what the majority of the world is doing. Also, it’s not just Europeans. It’s… Like every other country. So, why does America put the month before the day?
The Rest of the World
Turns out, the date formatting is actually quite a bit like America’s relationship with the metric system. Only the US, American Samoa, the Federated States of Micronesia, Guam, the Marshall Islands, and Northern Mariana Islands use the mm/dd/yyyy format exclusively.
Further Reading: Why Do We Have Both Metric and Imperial Systems?
The vast, vast majority of the world sticks to dd/mm/yyyy as a standard. No really, taking into account the main regions that use each method for writing down their dates, the mm/dd/yyyy format is used by only about half a million people.
By comparison, the main regions of the world that use exclusively dd/mm/yyyy have a combined population of 2.87 billion.
There’s one more common means of date keeping we haven’t addressed yet. Instead of putting the month or day first, there is a sizable population that puts the year first. It’s followed by the month and the day. The yyyy/mm/dd is still far more common than mm/dd/yyyy. Taiwan, China, Japan, South Korea, and South Korea make up the largest nations worldwide that use this format exclusively. The population exclusively using the year-first format numbers about 1.6 billion.
An Endian Issue
“Endianness” is a term typically used in computing, when determining how you want to order data. Commonly, big and little-endianness are the most common ways of sorting things. The former starts with the largest or most significant piece of information and moves progressively to the smaller ones. Little-endianness is the exact opposite.
That’s mostly shenanigans, but it can help us see why some regions stick to certain date formats. For example, typical grammar in Mandarin Chinese has speakers starting with the largest unit of measurement. This goes for addresses too, where provinces are listed before cities, then districts, etc. It’s a linguistic throughline that applies to everything—dates included. So it just makes sense that China, a primarily Chinese-speaking country, would list dates in the same way. Even names work this way, you’re probably familiar with how many Asian countries list family names before individual names even if you don’t speak the language.
So we can start by looking at dates with “that’s how people talk.” In English, saying you went to a concert on “2022, December on the 14th day” sounds a lot less natural than saying you went to a concert on “December 14th, 2022” or on “the 14th of December, 2022.”
While that explains why primarily English-speaking countries don’t use the yyyy/mm/dd format for dates, it doesn’t explain why America is so different. Unfortunately there doesn’t seem to be a well-documented answer. The most common thread we could find is that America took the mm/dd/yyyy format the UK used to use, and didn’t change to dd/mm/yyyy when the UK switched to mm/dd/yyyy. The US military uses dd/mm/yyyy, though. The dd/mm/yyyy format is becoming increasingly common in American industry, as well as academia and legal correspondence. So really it’s just us casual normies who are being weird. Just like we are… with metric.
Speaking of dates, see if you know what holidays share the same date here.
