we don't use leagues or furlongs. I know what a chain is because i have one, but that's specifically to measure land against a plat map. Every location in this country is based off common reference locations (there's a literal marker on the ground), with only chains and angles to delimit things (generally).

Read that last part again, because they use GPS to determine if the marker has moved, and that takes X minutes to quiesce. you can't take X*Y minutes to check each chain mark and angle.. not all land is rectilinear. we have a bit less than ten million km^2 of land in this country.

I'd reckon that maybe 1% of Americans know what a league is, as in the definition. Less for "furlong", less for "chain".

This is how these conversations go, usually. It's completely pointless, most of the people here will never interface with something where this matters. I'm a few decades old - 2.25 score years old, to be accurate. My wife knows what a score is, and how many feet in a mile, which i can never remember; by the by, it's about 5300 feet.

like Celsius, the metric measurements don't "mean" anything directly to a human. a meter is how fast light travels in 1/speedoflightinmeterspersecond. water boils at 100 and freezes at 0. compare to ~100F "roughly median body temperature", "roughly the length of an adult foot", and "roughly the length of the middle bone in your thumb".

yes, for "science" using units that convert is great, one of my favorite things to read is the Frink language unit file for that reason. Metric is cute and ostensibly "well-defined". great, use it.

you're not getting ~400,000,000 people to switch, potentially ever. The sheer cost is astronomical. a speed limit sign, just the sign is ~$22. The total cost of install could be from $500 to $3000. Per speed limit sign. There's at least 10,000 speed limit signs on interstates alone. [nearly] Every single mile of every single highway and interstate in the US has a reflective sign stating what mile it is - except for mile 420, i'm not sure why, that'll be missing but there will be a 419.7 mile marker. weird.

> In 2002, a contractor installed just over 50 miles’ worth of markers on I-78 and Routes 22 and 33 at a cost of $230,000, or about $4,500 per mile. Today, [...] $6,500 per mile, said PennDOT spokesman Ron Young.

and

> As of 2022, [...] the Interstate Highway System, which has a total length of 48,890 miles (78,680 km)

and that's just interstates. We have expressways, freeways, spurs, feeders, highways, state roads that use mile markers. Speed limit signs vary in distance, but figure 2 miles per (raelly 1 per mile since they're on both directions of travel, and usually there's 2 per direction, one on either shoulder) on nearly every commute surface. we have ~2,600,000 miles of paved roads, and a bit over 4,000,000 miles of roads, total, in the US - that's 6.437376e+6 kilometers, or 21 lightseconds in a vacuum, or 32 lightseconds in fiber optic cable. 32000ms ping, awesome.

Every house in the US is built with 16" on-center framing for the walls. we're not going to switch to "406.4mm on center", because our sheetrock, plywood, etc are all 48"x96".

every other country that switched did it 70+ years ago, has less people, or is drastically smaller.

like i said, rudely, but now politely, give it up, we're staying with our US customary units.

The Free Universal Construction Kit