Because gallon of fuel weighs 6lbs!

As a scientist and an adult immigrant to the US, I came to appreciate both systems as useful for different objectives.

Celsius/Metric is neatly rooted in science - where it truly shines by removing /most/ of the conversion factors (but does it? we still have, today, speed of light that should be 1, Avogadro and Boltzmann constants are just odd numbers you memorize too) - but doesn't match neither everyday weather and life (0F being "coldest you'll experience in a place humans commonly live" and 100F being "hotest", and close to wet bulb temperature and, through a fluke of an undiagnosed fever of Fahrenheits' wife, nice threshold for fever).

Fahrenheit/Imperial is actually relatively convenient to machining, industry and agriculture (but not engineering or science) - how much of that is actually fractional measurements (1/16th makes a ton more sense than 0.0625), and how much are the "fingertip/decent meal/daily water intake/sustains a person" idea of an inch/lb/gal/acre.. is quite intuitive. Far more so for composite units. 1 PSI is intuitive - you know what force to exert at what area of a piston, same for torque'ing to 80 lbs-ft.

But.. it makes a ton less sense when you separate N from kg (yeah, I am a physicist, I know why, it just makes less sense when building stuff in a dirty corner of an industrial revolution), then somehow apply it to a whole square meter to get a Pascal, and now you need decimal fractions of a million of those.. to represent what you actually see. Quick, do you think you can plug a 2cm diameter garden hose at 0.5MPa with your thumb to spray your dog?

CGS system was quite popular and useful, IMHO for that reason, at the time when Europe was actually manufacturing stuff and inventing them in barns and factories. But it was essentially "neither" - bastardization of sacred kg and meter - lost to SI.

US keeps inventing and making stuff in garages and fields.. and it shows in its devotion to imperial system. But I can see convincing mechanics to 1/8th of a cm and 40g way before I can see them taking up 1.25 mm and 0.04 kg.

NYC Apartment Aquaponics