I also want to mention that I didn't attribute the success of the US economy during the 19th century to the US Customary system (which is different than the Imp

I also want to mention that I didn't attribute the success of the US economy during the 19th century to the US Customary system (which is different than the Imperial System, btw). I said that the standard that was in place in America when the Industrial Revolution began was the US Customary system because the metric system was still in its infancy at the time and not widespread. By the time the metric system was established, widespread milling, machining, and lathing in the United States was all built around the US Customary system. There was already too much infrastructure to throw out over a marginal improvement. It's a simple economic problem. Does the cost of throwing out all the old machinery, equipment, fasteners, drawings, and tools justify the marginal benefits of switching to a decimal-based measurement system? So far, the market's answer has been no.