[img width=500 height=312.997]https://i.imgur.com/VMR7LS8.png[/img]
I think it was President Ford who made this mistake, maybe Carter.
Anyway, when I was a kid in the 1970's they said we were going to "gradually" switch to metric. That just inherently doesn't work. Nobody "gradually" switches from thinking "It is 110 miles to Ohio Stadium, that takes about two hours with traffic" to "It is 175 Kilometers to Ohio Stadium, that takes about two hours with traffic."
At this point in my life (I'll be 50 in about a week), I'm never going to feel "native" in metric. I'm too old to make that switch. Even if the US switched tomorrow, I think that for the rest of my life I'd still "think" in traditional English measurements and "translate" in my head.
They should have just ripped the band-aid off back in the 1970's. In that case I'd have learned metric growing up and traditional English would have been something I only used for working on old stuff.
The thing I'd like to know is how did they handle it with housing/lumber when the switched elsewhere?
2x4's are 1-1/2" by 3-1/2" which means that stud cavities are exactly 3-1/2" by 14-1/2" by (usually) 96". Switching that would take forever because all existing homes would be the old standard for literally centuries in some cases.