Other than the US (and a few other countries), the vast majority of countries use

  • International System of Units (SI).
  • Celsius temperature scale.
  • DMY or YMD date format¹.
  • 24-hour clock when written².
  • Monday as the first day of week³.

These differences can cause technical difficulties.

What are the historical reasons for the United States, which is one of the most advanced, powerful, and influential of countries, to keep using units and date representations which were abandoned by most of the countries of the world, especially developed ones?

¹ except the US, Philippines and a few other countries.
² except the US, Canada, Australia and a few other countries.
³ except the US, Canada, Mexico and a few other countries (also usually Saturday in the Middle East).

  • 19
    Even worse, the US actually tried to adopt the metric system in the 1970s or '80s, but the population en masse refused to go with the program and the plan was scrapped. There are still some remnants, like old roadsigns in both metric and imperial, that can be seen here and there.
    – jwenting
    Commented Mar 18, 2014 at 8:04
  • 14
    @Duncan I live in the UK, where people generally speak in imperial measurements (ordering a pint(which btw is not 500ml, it is 568ml), saying their height in feet and weight in stone), but metric is taught in schools, asked by doctors and used in pretty much every official way. This works very well, for both logic and keeping suitable terms.
    – Amber
    Commented Mar 18, 2014 at 11:17
  • 7
    I think the real question is "Why is the cost of standardization high? What are the factors driving the cost of migration to standards?" - and I'm not sure this is a history question. Economics.SE perhaps?
    – MCW
    Commented Mar 18, 2014 at 12:04
  • 21
    If you really want to capture the essence of why the United States does things different than the rest of the world, you may need to verse yourself with American history in general. There has always been a belief that the US is a special, ordained nation that deserves to be different if it wants. It's known as American Exceptionalism.
    – corsiKa
    Commented Mar 18, 2014 at 17:56
  • 21
    Actually, the US doesn't use Imperial. It uses American Customary Units, which are subtly different. There's a small difference in the size of a fluid ounce but the big differences are that a US pint is 16oz, compared to 20oz in Imperial; correspondingly, US gallons are smaller than Imperial gallons, since both are eight pints. The US hundredweight is 100lb (logical, huh?) but Imperial is 112lb (buuuuh?); since a ton is 20cwt, that means a US ton is 2000lb and Imperial is 2240lb. Commented Mar 19, 2014 at 1:23

10 Answers 10


The Status of the Metric in the United States
Strictly speaking, the US has been "metric" since the Mendenhall Order, issued in 1893. The inch is defined as exactly 2.54 centimeters, the pound (mass) is exactly 0.45359237 kilograms, the pound force is exactly 4.4482216152605 newtons, and so on. The conversion factors have changed a bit since 1893, but that there are defined conversion factors has not.

That said, there's a lot more to "going metric" than having some conversion factors hidden underneath the hood. There's a whole lot more to "going metric" than changing our speed limits and highway signs. Printing 453.6 grams in small print after a bold 1 pound on a can of peas is not "going metric", nor is exchanging the order of those units on that can of peas. Printing the size as 453.6 grams in bold and 1 pound in small, parenthesized print also is not "going metric."

"Going metric" means changing the size of that can of peas to 500 grams or 400 grams and printing the customary units (which will now be oddball numbers) in parentheses. It means changing the size of wires from American Wire Gauge to the metric wire standard, changing the sizes and pitches of screws and bolts from nice even fractions of an inch to nice even fractions of a centimeter. "Going metric" means changing the manufacturing base, from bottom to top.

European Measurement Systems in the 19th Century
No answer has yet mentioned the chaos of measurement systems in Europe prior to the French Revolution. Different countries each had their own system of units, or worse. Oftentimes, towns separated by a day's ride had their own systems of units. It was chaos, and it was that chaos that the French Revolution tried to address. There were no standards prior to the French revolution. Continental European countries addressed this chaos by switching to metric units. Metrication in western continental Europe was largely complete by 1876.

Other countries addressed that chaos in less draconian ways. Industrialization in the United Kingdom mandated having a consistent set of units. The UK Parliament did consider converting to metric units, but eventually instead standardized the informal units used in slightly different ways across the British isles in the Weights and Measures Act of 1824. This act cemented the use of imperial units in the UK until 1965. It was this standardization that formed the basis for the goofy units still used in the US (and informally, still used in the UK).

World Wars
No answer has yet mentioned the importance of centuries of war in Europe, culminating in the two World Wars. The two world wars wiped out the manufacturing base throughout most of continental Europe (and also Russia, Japan and China). They had to rebuild. The only system of measurements that made a lick of sense as the basis for that rebuilding was the metric system. Continental Europe was already metric. They weren't going to switch to the goofy British units.

It took those countries devastated by World War II twenty years to recover from the horrors of that war. The countries whose manufacturing base were not devastated? That would be the Commonwealth nations and the US. Manufacturing capabilities in continental Europe were bombed to oblivion during those wars, particularly during WWII. At the same time, the Commonwealth nations and the US underwent a huge build-up of their manufacturing base. This build-up was done using imperial units. There was a lot to lose in the Commonwealth and in the US by converting to metric. The Commonwealth countries were amongst the last to officially "go metric". The US? Not yet, but that too will come to pass.

The UK was the first of the Commonwealth nations to "go metric," and that only started to happen in 1965. By that time, 20 years after WWII, continental Europe had rebuilt their manufacturing base. Continental consumers liked having their cans of peas and all kinds of other consumer products expressed in metric units, and continental manufacturers liked having their screws, bolts, and all kinds of other industrial products expressed in metric units. UK manufacturers found themselves in the untenable position of maintaining two production lines, one based on imperial units for a small domestic market and another based on metric units for a potentially much larger export market across the Channel. The impetus for the British conversion to metric was largely industry-driven. The British people were steadfast against going metric; some holdouts still are.

Metrication in the United States
The US is a special case. No bomb were dropped on US cities, railway depots, or manufacturing plants during WWII. A large number of American soldiers did die in that war, but the US manufacturing base escaped the war unscathed. To the contrary! The US instead built up a massive manufacturing base during WWII. It was this build-up that resulted in the US being the world power after WWII. This build-up is also why the US has not yet "gone metric."

Unlike Great Britain, the US has a huge domestic market. Being attractive to that huge domestic market was key to survival for a US-based company for much of the post-WWII era. Exports? They were a nice add-on to the bottom line. Besides, for the first twenty years after WWII, what else were those outsiders going to buy other than American products? Europe and Asia had no manufacturing base. They bought American made products.

That calculus is changing. Just as it made no sense for UK-based manufacturers to have two production lines 50 years ago, it makes no sense for many US-based manufacturers to have two production lines now. If you own a recently built automobile, it will be metric through and through, It doesn't matter whether than car was built in Mexico, Canada, Europe, Asia, or Detroit. The US automotive industry has "gone metric."

That the US automotive industry has indeed "gone metric" will ripple throughout the US manufacturing base. This plus other aspects of globalization will eventually end the use of customary units in the US. The US will convert to metric units for the same reason the UK did: Those archaic customary unit make no sense from an industrial perspective.

  • 1
    I think this is a good rationale. It seems to be the same with the date formats. Some companies in the US and branches of the US government use American date format and some use the international standard. It depends on international market share.
    – Razie Mah
    Commented Mar 19, 2014 at 12:56
  • 2
    This is a great answer that addresses the sociological/economic reason behind the current situation and what would cause it to change. Commented Mar 19, 2014 at 18:23
  • 14
    Unfortunately I must downvote this. The metrification of continental Europe (with the exception of Russia) was already completed 1872, more than forty years before WWI. So there was more than enough time for the transposition of the manufacturing base before the war started. In fact, exactly for the correct statement that there were an unit chaos in Continental Europe the metric system was gladly accepted. Commented Mar 21, 2014 at 14:24
  • 7
    The automotive industry went metric a long time ago. The fasteners (nuts and bolts) in your car? All metric. If you're a backyard mechanic you absolutely need a set of metric wrenches because even your American-made car has metric fasteners. Deeper underneath the hood, the cutouts and fabrications? All metric. The US automotive industry has been moving toward the metric system since 1973 (and possibly earlier). Here's one reference: lamar.colostate.edu/~hillger/pays-off.html#gm . There are a whole lot more. Commented Mar 28, 2014 at 19:32
  • 2
    Great point about going "metric" referring to the change in commonly used amounts rather than commonly used units in measuring customary amounts! Although I mostly agree with that point, I'd like to dispute the further statement that changing the amounts implies changing the entire manufacturing base. This is not so: only that which is visible to end customers needs to be changed. And even for end customers sometimes customary amounts don't need to change. Entire metric World uses calibre 7.62 mm, mostly oblivious of it's being 0.3".
    – Michael
    Commented Sep 26, 2016 at 2:33

Edit: As pointed out in the comments, I realize this answer doesn't deal with the history of metrication in America. I intended it only as an answer to "why does the US keep using their systems?" However, other answers here do a very good job outlining the history, and I encourage everyone to check those out too.

As a non-American, I've always found it amusing that the 3 countries that officially cling to Imperial units are Liberia, Myanmar, and the United States. Quite a motley crew!

Anyway, for the US there are a number of reasons why it'll be hard to switch to metric/24-hour clocks/logical(!) date formats. Many of these reasons have already been mentioned.

But the simplest thing is probably a thought experiment for non-Americans: Imagine your own country wanted to switch to American units and formats. How receptive would you be to that idea?

Now setting aside the scientific arguments for using SI units, I imagine you would be very hesitant. It's not a lack of will, but an abundance of opposition.

These units and formats touch everybody's lives, meaning everyone is a stakeholder. Everything from grocery shopping to weather forecasts to your calendar would suddenly be a pain to figure out - just like it's a pain to figure out for non-Americans visiting the country. If you've grown up with one system, you've internalized it to such a degree that switching to anything else will seem completely ridiculous.

From the simple (replacing all your cookbooks) to the complex (retooling entire industries and changing every single road sign, to name a few), it's just a hornet's nest.

Sure, you can use rational arguments for why SI units etc. are just plain smarter, but if you're dealing with hundreds of millions of people, rational arguments tend not to work.

Add to that a certain anti-authoritarian streak that has defined much of American history and politics. If the US government declared that the country should switch to metric, I'd bet many would say that that's government interference in their lives. And they'd be right, because - as mentioned - it literally does affect everyone.

There could also be a wee bit of isolationism and perhaps even exceptionalism: Why should America even care what others are doing? And why should America follow anyone else?

And to many it will just seem like the stupidest thing to spend time and tax payer money on. To American eyes, there's no problem to solve. The US is self-reliant on almost everything, so as an American you never, ever have to deal with SI units for anything in your daily life. Goods are produced, sold, bought, and consumed by the pound, by the ounce, and by the gallon. No tricky conversions necessary.

Of course, the difference in units do cause problems. But it's not something the general public has to concern itself with. For instance, in 1999 an (unmanned) spacecraft was lost because one part of the system used Imperial units, while the rest used SI units. While that's the butt of many a joke (and a loss to science, but mostly a joke), it's again not something that affects anyone's daily life - especially since the craft crashed on Mars, not Earth.

So, in the end: Yes, America should absolutely switch to metric! It's crazy that they still use those weird systems :)

  • 19
    +1 for the very true but often overlooked fact that it's not enough to be a better choice, you have to be so much better that the cost of switching is worth it. Commented Mar 17, 2014 at 18:56
  • 3
    Welcome to history.stackexchange.com! This is a fine answer, although I might quibble with the notion that it doesn't answr the historical aspect of things (why we didn't switch in the first place, rather than why we aren't switching now). Commented Mar 17, 2014 at 19:18
  • 16
    This is not at all an answer to the question asked. All countries were in this position at one point, but most of them managed to get over it, and the US didn't. Why? This question doesn't touch on that at all.
    – RomanSt
    Commented Mar 18, 2014 at 13:09
  • 6
    "Imagine your own country wanted to switch to American units and formats.". I've lived in two countries that transitioned from one kind of unit to another, and over a couple of decades bother were fine with it. Commented Mar 19, 2014 at 13:28
  • 3
    A change of currency also impacts on many aspects of daily life. The European countries that switched to the Euro survived it anyway.
    – Antoine
    Commented Mar 13, 2017 at 18:34

With regard to imperial measurement, there is actually an interesting reason (at least in my opinion) why the US was not an early adopter of it. Thomas Jefferson had actually developed his own base-10 system of measurement (I believe he even attempted a base-10 system of time), and, had US relations been better with post-Revolution France, we may well have become one of the earliest adopters. Unfortunately, such was not the case:

The evolving political situation didn't help matters. Although France supported the American colonies during the Revolutionary War, it became hostile to the U.S. after Jay's Treaty was ratified in 1795. The French viewed the treaty, which eliminated British control of posts in the Northwest Territories and provided America a limited right to trade in the West Indies, as a blossoming alliance between the U.S. and England. France retaliated by sending privateers to target American merchant ships. By the time John Adams became president in 1797, the hostilities between the U.S. and France had grown quite intense. It's no surprise, then, that in 1798, France snubbed the U.S. when it invited dignitaries from foreign countries to travel to Paris to learn about the metric system.

Why isn't the U.S. on the metric system?

Now, granted, that does not explain why the US did not adopt the metric system, for instance, 40 years later, or 140 years later for that matter. Actually, technically speaking the US has adopted it since 1866 (see the same article above for more details), but as everyone living in the States knows, technical adoption is not the same as the population accepting it.

At this point, the largest reason we still cling to the imperial system is inertia. So much is in place that we think of via imperial measurements - your weight is in pounds, your height in inches, your milk in gallons, and so on - that at this point it would be a lot of work to change. Nevertheless, attempts were made as recently as the 1970s to switch over to the French system, and we're beginning to see metrics encroaching on all aspects of our lives as we accept the reality of global trade.

  • Yes - see XYZ Affair - the French wanted a huge bribe before they would even talk! The result was teh Quasi-War, and, eventually, the Louisiana Purchase. So the US didn't get metric, but they did get Louisiana! Commented May 16, 2016 at 21:07
  • 1
    Don't underestimate the significance of the existing install base. For example, switching from 8.5"x11" paper to A4 paper would involve replacing every filing cabinet in the country.
    – Mark
    Commented Mar 2, 2019 at 3:25

My answer is more about the metric system then about dates.

About dates, also consider that there are Chinese, Hebrew and Islamic calendar, which are much more different from the Christian one.

According to Wikipedia:

In 1866, Congress authorized the use of the metric system and supplied each state with a set of standard metric weights and measures. In 1875, the United States solidified its commitment to the development of the internationally recognized metric system by becoming one of the original seventeen signatory nations to the Metre Convention or the Treaty of the Metre.

But several decades later:

Congress passed the Metric Conversion Act of 1975 "to coordinate and plan the increasing use of the metric system in the United States". Voluntary conversion was initiated, and the United States Metric Board (USMB) was established for planning, coordination, and public education. The public education component led to public awareness of the metric system, but the public response included resistance, apathy, and sometimes ridicule. In 1981, the USMB reported to Congress that it lacked the clear Congressional mandate necessary to bring about national conversion. Because of this ineffectiveness and an effort of the Reagan administration — particularly from Lyn Nofziger's efforts as a White House advisor to the Reagan administration, to reduce federal spending — the USMB was disbanded in the autumn of 1982.

And even more recently:

On December 31, 2012, a petition was created on the White House's petitioning system, petitioning the White House to "Make the Metric system the standard in the United States, instead of the Imperial system." On January 10, 2013, this petition garnered over 25,000 signatures - exceeding the threshold needed to require the Obama Administration to officially respond to the petition. Patrick D. Gallagher, director of the National Institute of Standards and Technology, provided the official response stating that customary units were defined in the metric system, thus making the nation "bilingual" in terms of measurement systems.

Se also Metrication opposition (Wikipedia).

  • 8
    This answer just says that they did try and failed, but totally fails to explain why these efforts were rejected.
    – o0'.
    Commented Mar 17, 2014 at 15:03
  • It says that the main reason is lack of will to implement it and lack of money to invest in the modification of the current standard. Commented Mar 17, 2014 at 15:36
  • 1
    Sure but what is causing this lack of will? That's the real question.
    – o0'.
    Commented Mar 17, 2014 at 15:40
  • 2
    @Lohoris You're looking at it backwards. Where is the will to change. Excluding engineers/scientists (a very small fraction of the total population) most Americans never have any occasion to work with metric units in everyday life. Any argument about why it's better is going to founder against the fact that for 99% of the population the only thing they're going to see from the before side of a change is the problems involved in the switch. Commented Mar 18, 2014 at 21:21
  • 2
    What I personally expect to happen is a continued, mostly invisible to the average person switchover. ex over the last few years I've increasingly seen bottled water sold in 16.9 ounce bottles. 16.9oz = 500ml, and represents another product switching over without consumers explicitly noticing. For a lot of packaged food the same potential is present every time they decide to do a package shrink instead of a price rise (fewer consumers notice the former). Eventually I suspect most things will end up effectively metric without people noticing. Commented Mar 18, 2014 at 21:22

I'll start with about the only place actual history comes into this: why it started.

In English there are two ways to say dates:

America's official birthday is on the fourth of July, seventeen seventy-six.


America's official birthday is July fourth, seventeen seventy-six.

You may notice that the second way is far shorter. It requires no prepositions, which means it is much less awkward a phrasing. Easier for both the mouth and the ear. So it shouldn't surprise even a non-English speaker that this is the preferred and traditional way to say it for much of the English-speaking world.

When writing a date out numerically, what you are essentially doing is abbreviating. So if in English one typically speaks a date as "month day, year", then the proper way to abbreviate it (assuming slashes as separators) would naturally be MM/DD/YYYY. Any other way is going to confuse people (even if there is some standard somewhere saying it should be that way).

So where did the other order come from? Well, it turns out that in French, the natural way to speak a date is in fact "day month, year". So for a Frenchman, abbreviating dates as "DD/MM/YYYY" is the natural abbreviation. The Francophone world insists on that ordering, and will accept no other (as it would be confusing to them).

I won't get into the politics of who "won" when the EU standardized things. However, it should at least be noted that the capitol of the EU is in a Frankaphone country.

The USA is a much larger country (in just about every sense) than the UK, and does not have to worry nearly so much about French sensibilities. So it does dates the way its people want to do dates. If people in other countries have a problem with that, then they have a problem.

Now this being said, IMHO both systems are old systems. The "modern" way to do dates is in fact YYYY-MM-DD (aka: ISO 8601). This format is much easier for computers (and by extension, us Computer Scientists) to deal with.

The conversion to SI is a fairly different story, although the enemy is still established mindshare. Presidents Ford and Carter actually tried to move the US to metric back in the 70's. The general public balked, both were defeated in their next elections, and the next President (Regan) abolished the ineffective agency in charge of the effort. Today the USA uses Metric units in many of the sciences, but for the most part happily sticks to English units.

Generally it is probably the case that the USA is so large and self-sufficient of a society, that any radical change in units from what everyone is used to is nearly impossible. The vast majority of the population never has to deal with a non-USA person, so changing something everyone already understands solely for the benefit of this rarely dealt with non-USA person is just not going to fly.

  • 15
    Note that since everything runs on computers these days, and we program the computers, we computer folks will eventually win. Avoid the rush and get used to YYYY-MM-DD now.
    – T.E.D.
    Commented Mar 17, 2014 at 13:53
  • 18
    re your para about the UK, no one in the UK uses MM/DD/YYYY and everyone, even those who still fight against metric and cherish imperial regard MM/DD/YYYY as completely nuts. just saying. Commented Mar 17, 2014 at 18:48
  • 18
    Why the (almost paranoid) focus on the French? The notions that the metric system is, at this point in time, a French thing, that the French imposed it to the EU, that the DD-MM-YYYY order is specifically French or that whatever influence France still has in the EU depends on Brussels being in a (partly) francophone country are all bordering on nonsense.
    – Relaxed
    Commented Mar 17, 2014 at 19:50
  • 11
    @T.E.D. Well, it's quite simple. The EU has 28 members, many (most? all but two or three?) of them use the metric system and a language with the DD-MM order. Why even bother with the French language, Brussels, or “French sensibilities”? It does not make sense as an explanation.
    – Relaxed
    Commented Mar 18, 2014 at 6:53
  • 12
    As a German/Austrian I just wanted to reassure everyone worried about the French bullying us, that we had dd-mm-yyyy for quite a while longer than the EU exists :) All of my English friends (oh and one Scot) I know use dd-mm-yyyy as well and if they feel repressed about it they must be hiding it pretty well ;)
    – Voo
    Commented Mar 18, 2014 at 20:22

There's one thing people usually forget about "customary" measurement systems (aka "imperial" in this case): they are evolved over considerable period of time in the society, and thus are much more convenient for use in everyday life (where complex calculations are usually not required).

Lame examples were edited out due to popular opposition.

Natural fractions are also more intuitive then decimal one (one third, one quarter, etc). Thus, base 12 (as oft used in "customary" measures) is better for many purposes then base 10 (more prime factors to think with). Revolutionary (as in "French Revolution") French system (the direct precursor to SI) tried to mandate decimal measures for time and angular quantities - those were not accepted by anybody and faded into complete obscurity, while base 12 is alive and kicking.

Another interesting feature of customary systems, especially related to volume, was the use of base 2 system (each next measure is exactly twice the volume/weight of the preceding one).

In fact, while introducing many important innovations, French system was notoriously bad in choosing its étalons for most common measures. It was not mandated by lack of knowledge, but by a misplaced desire to remove the entirety of Ancien Régime legacy. Truly, customary foot makes a much better base length than a meter - apart from being more convenient in everyday life, the speed of light could be trivially defined as 1e9 feet per second, avoiding the need to work with a very cumbersome metric 'c' constant (to achieve this, modern definition of foot needs to be adjusted by only 2%; this is well within the original "customary" precision of foot definition).

Considering the above, it is not surprising that USA had never switched to the metric system:

  1. Relatively weak federal government and strongish local one, along with strongly opinionated population (with legal means to stand by their opinion) meant that people had a chance to stick to system they find convenient. For comparison, in continental Europe, metric system was introduced by the decree of the governments and with considerable level of violent oppression.
  2. Lack of real incentive, as most professional activities employ customized measurement systems (a good dozen of those is employed in physics/chemistry) or work with fixed sets of measurements. Standardization of those sets is of much more real importance than the underlying system employed, and it can be said that USA has much better standardization institutions than any other nation (NIST, ANSI, etc.).
  3. In the modern era all non-trivial computations are done by computers, which can do arbitrary unit conversions at negligible computational costs.

We can conclude from the above that large scale measurement system conversion will be a completely pointless exercise, which explains why USA never bothered (and probably would not bother in the future).

  • 5
    Some of your assertions sound rather contrived. You might have found a good table that is exactly 3 feet high, but most dining tables on the market are around 0.75m high (about 2.5 feet). It's about the same for typical office desks. Coffee tables are usually about 0.40m high. A table that was 3 feet high would be considered too high by many people.
    – tobyink
    Commented Mar 18, 2014 at 11:32
  • 5
    Further, if buying food to feed four, you don't go into a shop and ask for "four pounds of meal". Chances are you need lots of different weights of different ingredients. Whatever measurement system you're using, there's bound to be a few fractions in there.
    – tobyink
    Commented Mar 18, 2014 at 11:36
  • 3
    What a load of nonsense. A 1-liter beer is considered normal in Germany. The difference between one yard and one meter is too small to matter (and the height of a table is a really weird thing to take as a fundamental unit of measure). A centimeter is about the width of a thumb — that's even better than having to use two fingers. Whatever you may think of base 10 vs base 12, if you write numbers in base 10, that makes manipulating 10-based units easier (also, British units are not 12-based). Commented Mar 18, 2014 at 19:54
  • 9
    A good serving of beer is one pint agreed, clearly 473ml are the perfect serving size.. I mean 568ml are perfect - sorry I got confused were we talking about pints or pints again?
    – Voo
    Commented Mar 18, 2014 at 20:44
  • 5
    @oakad Going by population, about 95% of the world uses the metric system. Going by wealth, it's less, but I doubt that it's less than 50%. So no, US is not leading the world on unit standardization. I have no idea what traditional German beer sizes were. Commented Mar 19, 2014 at 0:26

The sheer size of the install base will ensure that American Customary measures will stick around in fact, if not in name. For example, if we go metric and a kid tosses a baseball through my window, I'll replace it with one that measures 122 cm wide by 91.5 cm high -- but that's just a 4-foot by 3-foot window dressed up in metric numbers. This extends to all sorts of things: for example, if you don't want to go around re-threading every single screw hole in the country, you'll wind up producing things like a M6.35x1.27 bolt -- the same thing as the UTS 1/4"-20 bolt, but with numbers that are far more awkward.

  • I'm not sure but I think that screw diameters are generally standarized in inches in Poland, so are the wrenches...
    – user1734
    Commented Mar 18, 2014 at 13:57
  • It's fairly common to refer to laptop screen sizes in "old" US units also elsewhere, presumably for reasons of convenience similar to the ones you cite.
    – Drux
    Commented Mar 18, 2014 at 15:29
  • 2
    This is probably on the right track towards a partial answer — it took several generations for France to convert to the metric system, but the place was less industrialized, meaning fewer objects needed to be adapted. Similarly, education was less widespread, meaning fewer people needed to adapt. Commented Mar 18, 2014 at 19:51

I can suggest a reason for continuing report weather Imperial Units. The benefit of Fahrenheit is that its scale is more granular. For every degree Celsius you get 1.8 more degrees of precision in Fahrenheit. Which when reporting the weather in Celsius it is almost only reported in whole numbers. Most of the time it's not a big deal, until it's very hot or cold in human terms. That's the second benefit of Fahrenheit, at 0 and 100 it's uncomfortable but not fatal to people

  • Fahrenheit
    • 0: Very Cold
    • 100: Very Hot
  • Celsius
    • 0: Cold
    • 100: Dead
  • Kelvin
    • 0: Dead
    • 100: Dead
  • 4
    The Farenheit scale was developed by Mr F to cover "normalish" temperature from 0-100. I think he used a ice-salt bath to get 0, and body temperature (more or less) to get 100. As a consequence, 0-100 covers the range of all but the most extreme weather conditions without using three digit or negative numbers, which was important in the days before weathermen started inventing "shock" measurements like humicure, windchill, and so on
    – Oldcat
    Commented Mar 17, 2014 at 21:59
  • 7
    You could turn around your 0/100 argument by looking at "the medium-sized numbers" that people are used to dealing with... say 18/30. In Celcius, they're both reasonably comfortable; in Fahrenheit, they're both uncomfortably cold; in Kelvin, you're dead. My choice of 18/30 is of course completely arbitrary, but so is your choice of 0/100, unless you think 100 is a number that people are especially comfortable dealing with, in which case it's a pro-metric argument.
    – tobyink
    Commented Mar 18, 2014 at 11:42
  • 5
    Fahrenheit only has greater precision if you restrict yourself to integers. Weather forecasts do tend to restrict themselves to integers, but given the typical accuracy of weather forecasts, the Celsius is scale is more than adequately precise! The main reason to adopt Celsius over Fahrenheit is the same reason it makes sense to switch from barleycorns to centimetres: even if barleycorns offer a greater precision, more people worldwide will understand what the hell you're talking about with centimetres.
    – tobyink
    Commented Mar 18, 2014 at 16:06
  • 3
    The thermometers encountered by most people are almost never accurate to better than ∓1°C - so greater precision is misleading. Where greater precision is needed we can write 20.4°C (instead of say 68¾°F) - so it's hard for me to see this "granularity" as a significant characteristic. Commented Mar 18, 2014 at 16:23
  • 4
    0/100 C arbitrary? How about 32/212 F? Ever heard of water freezing or boiling? Commented Mar 18, 2014 at 17:41

it would be too easy to just wake up and actually LOOK at the metric system, see the logic of how easily you can specify how many centimeters are in 5.3 kilometers (so, the first clue is that the actual prefixes in the metric system MEAN SOMETHING- aka centimeter has 100 to a meter, as centi would indicate. then you have kilometer- which would indicate 1000 meters... so you have 5,300 meters times 100, and thus even a moron can see that 53,000 centimeters constitute 5.3 kilometers)

instead, people in usa rely on what people everywhere else rely on on all manner of issues: stubbornness and ingrained habitual responses. these are actually the way the entire human race deals with change. it just so happens that the entire course of history since the industrial revolution has contributed towards ingraining this particular set of practices in americans, much the way the irish or polish ingrained the potato into their cuisine: it just sort of stuck.

trying to promote change, while often perceived as helpful or necessary, in an uphill battle when dealing with humans due to this "conservatism in spurts" whereby certain systems may be very flexible but suddenly harden as usage piles on. This is much as a production web server will often never get its updates and minor fixes, as there simply is no more concept of downtime for maintainence. oops.

  • 6
    Starting a holy war is probably a bad idea. While there're clear advantages of using base ten units when relying on a base ten numeric system, base twelve units have clear advantages in everyday use too — there're more ways to divide 12 than 10 (2, 3, 4 and 6 vs. just 2 and 5). We're still using base sixty (!) time units, if you've forgotten. Actually, if I were designing the world from the ground up, I'd rather change the base of our numeric system to 12 (for easier division) or to 16 (for easier interaction with computers), than change measurement units to base 10.
    – Athari
    Commented Mar 19, 2014 at 5:30
  • 1
    @Athari - Time and angle are the two things the French failed to metricize. There's a good reason: Widely accepted standards (based on non-decimal bases) already existed at the time of the French Revolution. We have the Egyptians to thank for our 12 hours in half a day, the Babylonians for 60 minutes per hour, 60 seconds per minute, and 360 degrees per revolution. Scientists, engineers, and anyone else who cared about time or angle knew those already standardized units. Where the French Revolution added value was how we express distance, mass, and force. Commented Mar 19, 2014 at 6:44
  • 1
    Of course 60 is a very conveniet 5*12 time is actually base 12.
    – jwenting
    Commented Mar 19, 2014 at 11:55
  • @DavidHammen, actually, decimal time was part of the original French metric system (either 10 or 20 hours per day, of 100 minutes each, IIRC). Is was wildly unpopular in France, and soon abandoned. There still exist clocks built to display this time (often with a hidden traditional face). Sometimes you will also see "gradians" used in angle measurement, where 90 degrees = 100 gradians. I've never seen it actually used anywhere in practice.
    – Phil Perry
    Commented Mar 20, 2014 at 16:09
  • @PhilPerry - That's correct. So why aren't those part of the metric system? The French concepts of decimal time and angle never caught on because widely accepted standards for time and angle already existed. We have twelve hours in half a day thanks to the ancient Egyptians. We have sixty seconds in a minute, sixty minutes in an hour, 360 degrees in a circle thanks to the ancient Babylonians. Distance and mass measurements were in a state of chaos. Time and angle weren't. There was no impelling reason to change the latter set. Commented Mar 20, 2014 at 19:16

The answer is quite simple. Freedom. In the United States individuals are free to choose whichever system they want to use, and the government does not yet have enough power to force them to use a different system. So the milk bottler that has been bottling his milk in gallons, half gallons, quarts, pints and half pints will continue to do so, because that is what he is tooled for, and that is also what his customers demand and understand. He has a considerable economic advantage to continue using the same units. We have a constitution that is supposed to limit the power of the government, and so far that has prevented a switch of units by fiat.

In order to understand this answer, it is instructive to look at the metrication process in Britain. All it takes is a little research into this Britain's history with the metric system to see that this question is kind of based upon a false premise. I have found news articles lamenting the fact that Britain uses a mixture of imperial and metric units (Will British people ever think in metric? http://www.bbc.co.uk/news/magazine-16245391). I recall a time I was visiting one of my English friends from college. I sat down by him on the bed and my weight created a depression, pulling him toward me. He jumped up and exclaimed: "Good Lord, you must weigh 16 stone!". He was spot on by the way, that is almost exactly my weight.

Ok, so now back to the history. Below is an excerpt from wikipedia on the Metrication of the U.K. (http://en.wikipedia.org/wiki/Metrication_in_the_United_Kingdom)

Adopting the metric system had been discussed in the Parliament as early as 1818 and some industries and even some government agencies had metricated, or were in the process of metricating by the mid 1960s. However, a formal government policy to support metrication was not agreed until 1965. This policy, initiated in response to requests from industry, was to support voluntary metrication, with costs picked up where they fell. In 1969 the government created the Metrication Board as a Quango to promote and coordinate metrication. In 1978, after some carpet retailers reverted to pricing by the square yard rather than the square metre, government policy shifted, and they started issuing orders making metrication mandatory in certain sectors. In 1980 government policy shifted again to prefer voluntary metrication, and the Metrication Board was abolished. By the time the Metrication Board was wound up, all the economic sectors that fell within its remit except road signage and parts of the retail trade sector had metricated. The treaty of accession to the European Economic Community (EEC), which the United Kingdom joined in 1973, obliged the United Kingdom to, incorporate into domestic law all EEC directives, including the use of a prescribed SI-based set of units for many purposes within five years. By 1980 most pre-packaged goods were sold using the prescribed units. Mandatory use of prescribed units for retail sales took effect in 1995 for packaged goods and in 2000 for goods sold loose by weight. The use of "supplementary indications" or alternative units (generally the traditional imperial units formerly used) was originally to have been permitted for only a limited period. However, that period had to be extended a number of times due to public resistance, until in 2009 the requirement to ultimately cease use of traditional units alongside metric units was finally removed.

The Quango (quasi-autonomous non-governmental organisation) was active from 1969 to 1980. This period represented the largest jump forward in metrication since the process began.

By the time the Metrication Board was wound up, all the economic sectors that fell within its remit except road signage and parts of the retail trade sector had metricated.

These Quangos are non-governmental organizations to which the government gives power and funding. Because these Quangos are non-governmental and somewhat autonomous, they can exert power against the will of the people and the people have very little recourse. These Quangos appear to be a failed experiment in autocracy, as the UK is in the process of defunding and eliminating many of them. There have also been accusations that the appointments to them are based more upon political patronage than qualifications, and they are very expensive for the services they provide.

In his recollection of his time serving as head of the Metrication Quango, Jim Humble, appears to validate the 'metrication by force' hypothesis

High Street retailers found enormous commercial advantage in reverting to sales by the square yard. Consumers could not be persuaded to believe that goods costing, for example, £10 per square yard or £12 per square metre were virtually priced the same. Consumers bought, in very significant volume, the apparently cheaper priced imperial version. Metrication of carpet sales entered into full scale reverse and the Chambers of Trade and retail associations pressed for firm Government leadership, i.e. compulsory cut-off.

What would have been the result if the members of the Quango were elected officials, answerable to their constituents? Compare to the Metrication Process for the same time frame in the US.

Voluntary conversion was initiated (1975), and the United States Metric Board (USMB) was established for planning, coordination, and public education. The public education component led to public awareness of the metric system, but the public response included resistance, apathy, and sometimes ridicule.[7] In 1981, the USMB reported to Congress that it lacked the clear Congressional mandate necessary to bring about national conversion. Because of this ineffectiveness and an effort of the Reagan administration — particularly from Lyn Nofziger's efforts[8] as a White House advisor to the Reagan administration, to reduce federal spending — the USMB was disbanded in the autumn of 1982.

The USMB in the US reported that they were unable to bring about change because they lacked the Congressional mandate necessary to bring about national conversion. Translation: They did not have enough power to force the people to incur the costs of switching. It is clear that in both of these cases that the cost to switching to metric system was quite high, and individuals are unwilling to foot the costs unless it is by force. Indeed, it seems that they had a considerable economic advantage to staying with their existing systems.

  • 9
    This answer is wrong. The FPLA denies Americans the freedom of selling goods with units other than those set out in US law. Commented Mar 18, 2014 at 15:49
  • 1
    RedGrittyBrick, It sure does. Note that I did not say that our constitution fully protected us from government force, but that is it's intent. I think it is also notable that the requirement to add metric units wasn't added until 1994. There are many government agencies and regulations that are acting with unconstitutional authority. The question is how much influence can they exert on the people before the people push back. The story of the twentieth century in America is that of creeping government tyranny, with occasional popular awakenings and a move back toward more freedom.
    – Mauser
    Commented Mar 18, 2014 at 16:27
  • 1
    The comments section is not a discussion board. Please take your comments to The Time Machine, which is intended to be used for prolonged discussion. chat.stackexchange.com/rooms/1560/the-time-machine
    – ihtkwot
    Commented Mar 22, 2014 at 19:11

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