Because there’s no reason to switch.

we do! one inch is exactly 25.4 mm. fluid volumes are almost always seen in both standard measure and metric. most disposable plastic water bottles contain 500 mL of water. lots of engineering for american stuff is actually using metric measures too, including automobiles!

other places use the standard measure as well. in canada, you'll construct something with 2x4s and 4'x8' sheets of OSB. in the UK, oh goodness... it's a complete catastrophe. you'll see distances in kilometers but speeds in miles per hour, and don't even get started on stuff like body weight measured in stone, or the breakfast cup (these are actual, real units!)

a very good example is altitudes of aircraft. except for russia, china, and some ex-soviet nations, it will be in feet (or hundreds of feet; "flight level" 320 is 32 000 feet!). this holds true from the bahamas to japan to lithuania. the speed unit knot is a bit weirder, doesn't neatly fit into either boat (pun absolutely intended), and is worthy of its own write-up.

whatever units you use, really our main suggestions would be to follow in the footsteps of the SI (even if using non-SI/non-metric units), be clear, and be consistent!!

stay safe and happy measuring :)

Originally it was because the ship carrying the official metric measures from France to the US in 1793 was captured by pirates. More recently it’s because there was a near-revolt when Jimmy Carter tried to reintroduce it in the 1970s in an attempt to make the US even slightly less regressive.

because they industrialized before metricalization and it would've been incredibly expensive to convert all their machines and tooling to metric afterwards. same reason as the UK. a lot of places industrialized later, in metric from the start, and didnt have this problem.

and then they became the hegemon, and didnt have to convert, because fuck you, why should i cooperate with vassals.

the US will convert to metric when it sinks to the level it deserves and the customary units become a pain because nobody else is willing to deal with them and all the importable equipment is in metric.

Because “‘MURICA” okay?

Because the entire country has a foot fetish.

As a science teacher, when I see a worksheet online mention inches or pounds, that open tab on my browser closes at a rapid speed.

USA uses both, just like the UK and Canada. It's standard in the states for...medicine, the military, science, and... two-liter beverage bottles.

Technically they do. The US units are defined by the metric system, and they are full members of the Metre Convention since 1878.

Officially, we're the only ones still using imperial units. But, the British use a mash-up of units in their daily lives, as does Liberia and Myanmar.

Reagan pulled the plug on our attempted conversion in 1980.

We'll convert someday, probably after our imperial reign is over, somewhat fittingly.

Because my car gets 40 rods to the hogshead and that’s the way I like it!

We're a stupid country rules by assholes and morons.

You just know if someone tried to make a serious push for it, all the fox news types would go into a frenzy. It'd be an easy way to whip up their idiot base.

The US uses the metric system. SI units are provided by Federal Government for almost every quantifiable product produced by a federal agency and its been like that for decades. Often they use a mix of customary and SI units, providing conversions between the two in official reports. Generally you see customary units communicated when work more directly impacts the general public with more technical work using the SI system. Many industrial fields use predominantly the metric system as is the case for medicine and many engineering fields.

The US does not use, exclusively, the metric system because many units had been adopted by convention prior to the formalization of the modern international SI system and for cultural or historic reasons people don't want to change.

That's not so different from other places where measurement systems in common use are often retained.

The metric system debate is, for me, one of the most interesting cultural bugbears on the internet. Because it does not really matter that much what system of measurement a nation uses, its really not going to impact your life that much at the end of the day. Particularly in the modern era where conversion is as trivial as looking up a calculator online. But for whatever reason people get huffy about the metric system.

Not the only country Liberia uses the imperial system too.

I think its more odd that many countries use a mix (e.g. the UK with units like stones and some lengths in imperial while others are not)

Americans aren’t taught the metric system in school in a way that would force them to understand why it’s better. American education rarely teaches life skills, and in my case, almost none at all even though I was a full honors student at a top high school.

Nation of proud morons. Most of them do unofficially anyway

My theory is that the federal nature of the US leads to a default popular attitude of hostility toward any policy that originates above the state level, unless there are commercial interests willing to pay for the marketing and campaign contributions to sell it to the people and/or legislators. And businesses aren’t that interested in an improvement that only marginally affects their profits.

We use both