The US doesn't use Imperial units. It uses US customary units, which are different from Imperial in several significant ways, because the Imperial system evolved after the US split from the British Empire.

Also interestingly, US customary units are defined in terms of metric. So in a sense, the US does use the metric system.

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

I often correct people regarding the US not using Imperial as well but to be fair the only significant difference these days is in fluid measurements. Weight and length measurements were standardised between US customary and Imperial back in the 1950s

https://en.m.wikipedia.org/wiki/International_yard_and_pound

That is good to know. Also linked from that article:

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