[dazhengca]

Metric is currently the “ preferred system of weights and measures for United States trade and commerce”

https://uscode.house.gov/view.xhtml;jsessionid=8314B6B7A95CC...

As you mentioned, the foot and all other U.S. customary units are based on the International System of Units (SI).

https://www.nist.gov/pml/weights-and-measures/metric-si