There are 24 hours in a day, but not every country is in agreement on how these 24 hours are measured on a clock. Most countries use the 24-hour clock, while 18 countries use a 12-hour clock that measures both am and pm. Among these countries are Australia, Canada, Mexico, New Zealand, and the United States.
However, most militaries that include the United States, use a 24-hour clock that’s called military time. The world had been more split down the middle on the 24-hour clock usage until the 19th century. That’s when Sir Sandford Fleming missed a train because the hours for am and pm weren’t listed. He set out to make the 24-hour clock a worldwide standard, and after some adjustments resulted in Coordinated Universal Time.
It might seem silly now to think that someone would get am and pm confused, it was a common occurrence in the 19th century. If it could fool someone of Fleming’s intelligence, it could certainly fool the average person. After all, Fleming was an engineer and brilliant inventor that was highly influential in the development of Canada heading into the 20th century. Interestingly enough, Canada is one of the few countries that didn’t adopt his 24-hour clock.
Fleming moved from Scotland to Toronto at a young age and helped to engineer many of the railroad tracks used in the Intercolonial and Canadian Pacific Railways. Fleming even designed the first postage stamp in Canada and founded both the Canadian Institute (now RCIScience) and Royal Society of Canada.
Just seven years before the 20th century, Italy became the first country to officially adopt the 24-hour clock as the standard measurement of time. It wasn’t long until other countries followed suit, especially during both World Wars. Eventually, the 24-hour clock became the standard for a majority of countries around the world, though some of the major countries previously mentioned are still on the 12-hour clock system.
In the United States, the 24-hour clock is still known as military time. The key reason for this is that the primary use of the 24-hour system in the country is used by the military to coordinate with a majority of countries. The United States first started using military time during World War I, but only in the Navy. The United Kingdom’s Royal Navy adopted military time in 1914, with the Army following suit in 1918. The Canadian military went into military time in 1917.
It wasn’t until the second World War (1942) that the United States Army adopted the 24-hour clock. The matter in which the 24-hour clock is read and spoken is agreed upon between the United States military and English-speaking allies, most notably the United Kingdom and Canada. While in the United States it may be 9:00 am, the military would refer to it as 0900, or zero nine hundred hours).
Over the years, there have been talks about the United States adopting the metric system and permanent daylight savings time. However, there have been very few pushes to adopt military time into civilian use. As the years go on, the pushes become fewer and farther between, too. A big reason for this is how familiar the 12-hour system is, as well as technology making it much easier to track and clarify the difference between am and pm.
If you’re in the United States, it can be easy to identify someone that has had a bit of military service depending on how they tell you the time. If the word “hundred” comes up for any time of the day, that’s a dead giveaway of military time. It remains to be seen if countries like the United States or Canada will adopt military time into everyday use, but for now, it’s reserved for members of the armed forces while civilians continue to work the 9 to 5 instead of the 0900 to 1700.