Well, the USA does not use Imperial measures.
Our money is metric, our temperatures are Fahrenheit, and most of our other usage is traditional US measures. The US traditional system was standardized well after the metric system was determined (by Thomas Jefferson, no less) to be inappropriate for most of our uses (that situation has since changed - metric is very appropriate to the DNA labs and suchlike that we didn’t have in the 18th century) and well before Imperial units were created.
As for the guy’s question, sixteen is an OK number - three whole divisors not counting itself and one, and one of the divisors is 2, so you can make a measure or scale extremely easily without lab equipment or electrical power. A bit more practically useful in the field than base ten, which has only two such divisors, but far less useful than base 12, which has four whole divisors including three, which is super useful since it’s commonplace to need to divide by three for creative/constructive purposes.
