While the 95 percent of the world has converted to the metric system, the United States stuck with inches, feet, ounces, pounds, Fahrenheit, etc. Only two more countries accompany us in this resistance against adopting the International System of Units (SI): Liberia and Myanmar (Elliott-Gower). After more than 200 years, we are still “on the other side”. We need to fix it ASAP.
The very first opportunity to go metric was missed in the early 1800s, when “President Thomas Jefferson, an amateur scientist and mathematician, recognized the merits of metric, and there was a lot of pro-French, anti-British sentiment in the country”. Then, in nineteen century, the US government authorized the official use of metric measures, alongside British measures in 1866 and signed the Treaty of the Meter in 1875.

Draft NASA Constellation Program Management Directive Regarding Use of English Units of Measure

"3. RATIONALE: This directive defines and communicates a consistent approach to the use of engineering units throughout CxP. The program conducted an extensive and detailed effort to implement a primary SI units based system for design, analysis, test and operations while allowing English units for most of the hardware.