The American Kilogram

Anyone who wants a definitive answer to the question of how much a kilogram weighs has to visit NIST and order a stainless steel cylinder calibrated against the precise weight of K20 or K4.

The US signed the metre convention and bases all customary units on SI standards. As an aside, the Utah constitution from 1895 required the metric system to be taught in schools.

 This requirement was repealed in 1987.