I'll believe the US is using metric when you can buy rice by the kilo, gas by the liter, paper in ISO sizes, and construction sheet goods in increments other than 8x4 feet.
Non-metric preferred sizes are embedded everywhere.
The Carter administration attempted to start a full transition to metric in the late 1970s. When Reagan took power this was killed and no one attempted to revive it, because it was turned into a nationalist thing, one of those things Republicans reflexively oppose.
Non-metric preferred sizes are embedded everywhere.