The US is a dual system-- people are free to use whatever system they want, but business is encouraged to use metric, especially for trade. There was a big pus

The US is a dual system-- people are free to use whatever system they want, but business is encouraged to use metric, especially for trade. There was a big push in the 1970s to teach and adopt the metric system on a broad basis-- I remember there were even km speed limit signs-- but it failed. Americans think in feet, inches, miles, gallons, and pounds....imperial still has the first-mover advantage 400 years later!