Man, the progressive school (Comanche Elementary in Overland Park, Kansas!) must have had a huge impact on my life. In addition to open classrooms (I was in Unit 5, not 4th Grade), team teaching, a focus on experimental science, a circular layout to the school with a sunken (architecturally) library in the center…

Yeah, we went over the Metric System that whole year. I can still sing the "Metric Family" song from the film on metric units ("Kilo", "Milli", etc.). And to my young and impressionable mind, the U.S. was joining the rest of the "Free World" in a kind of Star-Trek-like casting aside of the old things that divided us—joining each other with a focus on progress, science, space…

President Carter came along around the same time or shortly after. And I have a photo of a family road trip to South Dakota, Montana: the sign that indicates the altitude of a particular mountain pass has both feet and meters. I Google-mapped the same location recently and of course it's no longer in meters.

I feel like in my elementary school days (the 1970's) the U.S. was on the cusp of a future of optimism—no doubt buoyed by having put astronauts on the Moon, but I was wildly on board for it.

But then some kind of shit seemingly started to poison the country. I don't feel we have ever returned to that level of national optimism. Perhaps 1976, the Bicentennial, was the end of it. (Recently watching the film "Nashville" brought me back a bit of the vibe of the times.)

I've been missing it my entire life since.

1. "They're more intuitive". They're not. You're just familiar with what 70 F feels like. If you're used to metric, 70 F is meaningless, but you intuitively know what 20 C feels like.

2. "Metric leads to lots of awkward numbers." All systems will fortuitously have round numbers in some contexts and awkward numbers in others. Customary units are different in that there are awkward numbers baked into the system. e.g. 5280 feet in a mile. 128 ounces in a gallon.

3. "It's too much trouble to change." You're already using metric units. U.S. customary units have, metrologically, been defined in terms of metric units since the Mendenhall order of 1893[1]. i.e. A meter is defined in terms of how far light can travel in a period of time defined by a hyperfine transition frequency of Caesium. If you needed to know exactly how long a meter is for a very precise measurement, a reference meter could be produced in a lab by aliens who have no idea what a meter is by using this definition. No such definition exists for a foot or yard. Nobody maintains physical reference yards (the old-school method) anymore. If you want those aliens to measure out a yard precisely, you tell them how to measure out a meter and then tell them 1 yard = 0.9144 m.

[1]https://en.wikipedia.org/wiki/Mendenhall_Order

Fahrenheit has more precision without using decimals for the thing 99% of people are using temperature measurements for: air temp. Where I live, we generally experience 5 degrees F - 100 degrees F at different points of the year. That's 95 degrees of precision with no decimal. In C, that's -15 to 37.8, a mere 52.8 degrees. The difference between 75 (usually a beautiful day) and 85 (hot) is 23.8C to 29.4C. Everything packed into this tight range.

Inches/feet being base 12 divides better into thirds and fourths, which is very useful in construction.

For science, sure, I'll use metric.

For those wondering why there is this distinction, the British Imperial units were created by the Weights and Measures Act 1824; US customary units follow the Winchester Standard of 1588.

There are many more fun and exciting non-metric measurements you might encounter than plain old fractional inches.

A fabricator might encounter sheet metal thickness in "gauge". Wire sizes, ammunition, and machine screws also come in "gauge" sizes but all four are different scales. US drills come not only in fractional inch sizes, but letters and numbers as well. Furnace efficiency is often specified in percent, but air conditioner efficiency comes in SEER. Water softener capacity is in "grains". Pipe threads come in "inch sizes", but that usually means NPT. Metal hardness and rubber durometer measurements have their own scale which doesn't really belong to either camp.

To be fair, a lot of these are categorical units. Screws come in #2 or #6 or #4, but you'll never need to worry about #3.7.

A wise professor once told me "All these different units will not be going away within your lifetime, so you better get used to working with them."

Every time the USA manufacturers something that isn't metric, you've made it incompatible with the rest of the world. The USA got away with that when I was young because they were the world manufacturing powerhouse. Now, those powerhouses are based on Asia. They define the units most of the world sees, and they use metric. So if I buy a Chinese mower, all the bolts are metric and I'm guaranteed the local hardware store stocks them.

Time has moved on, the USA is now a follower, not a leader in most things bar digital services. If they want to return to selling those things to the world the speeds have to be in km/hr, weights in kg, sizes in mm or meters, the temperature in Celcius, pressures in Pascal's.

https://www.nist.gov/blogs/taking-measure/pirates-caribbean-...

Similarly, a 1/4-20 bolt will fit in a M6 tapped hole if you use a large enough hammer.

A hazardous aspect of US threadforms is that #10-32 machine screws and #8-32 machine screws have the same pitch. So you can fit #8 bolts in a #10 hole and sometimes, they FEEL like they made good torque, because they engaged one side of the tapped hole, when they really have no tension capability whatsoever.

Reference the British Airways flight 5390 accident where the pilot got sucked 3/4 the way out the cockpit window and slammed against the side of the fuselage while a flight attendant clung to his feet and the co-pilot safely landed.

Also note that a British designed and built product was using US threadforms...

https://admiralcloudberg.medium.com/the-near-crash-of-britis...

https://en.wikipedia.org/wiki/British_Airways_Flight_5390

https://www.sfgate.com/travel/article/how-kilometers-appeare...

I noticed a couple of years back that my "U.S. Customary" wrenches weren't fitting my new plumbing fittings which were definitely not metric, but metric wrenches did. Probably made in China.

Then last summer I noticed something similar with lag bolts. The U.S. Customary socket fit the head, but it was nearly identical to a metric one that fit just a little better. The threads are designed to go into wood, not a nut, so if they were metric you'd never even know.

When I was designing stuff here in Canada, that was basically Wednesday. One big advantage of the USA withdrawing from trade is that Canada will have the opportunity to finally complete the metric conversion.

In ordinary every day life, I've found that I use metric for measurements under an inch or under an ounce. At a certain upper limit it makes more sense to use metric for large values too.

So I have to suffer with the magic constant 25.4 bouncing around my brain every day forever and constantly converting trivial measurements into worse units.

I will never convert a measurement to fractional inches. If you must have inches as an input you can suffer a damn decimal point.

Also a great use for LLMs. I'll tell it to convert recipes from volume to grams by estimating density. It's surprisingly accurate

Woodworking became a lot more enjoyable- I don't know why- when I started to think "I need to shave off 1mm" instead of "shave off 3/64 inch" or whatever.

And every science class I've ever had was exclusively SI units. Except for Thermodynamics, which sometimes uses BTUs and steam engines.

Unless someone comes along and forces it on you, for the average person, there’s not enough incentive to switch.

https://www.youtube.com/shorts/XiEM57ifX54

The only people who benefit from a switch to metric are kids (cause they won't have to learn the imperial conversions). And they, for better or for worse, don't get a say. If people really want the US to switch measurements so badly (which I have no idea why anyone gives a shit what our country does, it's not like it affects them), then they need to come up with an actual compelling benefit to adults in the US if they switch. 100 years ago there was one: you can do conversions more easily. But today there is not, and until one surfaces there's going to be zero pressure to switch units.

Like programming languages and UIs, it's what and how people use them. Imperial tends to be better because it's more "evolutionary."

There is no super-slow "conversion" of the US to metric.

There is a super-slow adoption of metric _alongside_ the "customary" Imperial system.

96% of the world’s population and 75% of its nominal (but not PPP adjusted!) GDP is metric.

All science is metric.

Other arguments simply don’t matter. How fine the Fahrenheit vs Celsius scales are or whatever is pointless, irrelevant debate.

Join the rest of us, or slowly fade into irrelevance. There is no third option.

You’re that one mansion with the doddering old cranky fool still lighting their place with town gas while everyone else has been using electric lighting for decades.

The next time the street is dug up, your pipes won’t be reconnected.

“So what if our spaceships occasionally crash into Mars at full speed because we got mixed up with our units… again? We can afford it!” — apologists.

There are many reasons I can find for leaving the US, but engaging in DIY projects utilizing local suppliers are what's come closest to pushing me over the edge. Especially in this post-SEARS hellscape of low quality made in china junk the market's flooded with. Now not only can I never find the fasteners I need, the tools suck too!

If you want to try to understand why the US is so fucked up, just look at England...