Back in the day when we were developing a measurement system, we used whatever was closest, and what was closest was our bodies. We had actual measurements such as "an arm's length," "a foot," and an acre, which was the amount of land that a person could work in one day. But all the while as we in the United States were developing our own unique system, France was disseminating their system, based on the number 10. Called the metric system, it spread and took hold throughout much of Europe, creating a fundamental divide between Europe and the US that impeded trade. So what did the US do?
In order to rectify this divide, in 1866 Congress signed an act agreeing to recognize the metric system as the global authority on all units. So why are we still not using the metric system? Turns out we actually are, it's just disguised by our own unique vocabulary. The governmental definitions for all of our units are actually defined by their equivalents in the metric system; i.e. 1 mile = 1.609344 kilometers, not the other way around! In 1975, President Gerald Ford signed the Metric Conversion Act to try to get the US to fully adopt the metric system, but because the act was made optional, it essentially failed. Turns out here in the US we're really stuck to our ways!