See the summary here: https://en.wikipedia.org/wiki/Metrication_in_the_United_States https://en.wikipedia.org/wiki/Metrication_in_the_United_Stat... You should

See the summary here: https://en.wikipedia.org/wiki/Metrication_in_the_United_States https://en.wikipedia.org/wiki/Metrication_in_the_United_Stat... You should be long past asking about why, and should be asking why it didn't happen years ago.