Transition to global measurement harmony typically falls into one of three common categories:
The first category is the quick Big-Bang scheme which India prefers in the 1960s as well as several other nations including Australia and New Zealand since then.
The second category is to gradually phase in units over time and progressively outlaw traditional units. Industrial nations prefer this scheme, but it is generally less complete and slower.
Japan has been at it for over a hundred years and their status of metrication is “almost entirely complete” — now that is pretty slow!
The third category is to redefine traditional units in metric terms. Places like China where traditional units are ill defined and have regional variations find success with this method.
Some Americans find every excuse under the sun to scoff at proponents of metrication. But American Exceptionalism is actually a hindrance, not a benefit.
Should the United States Congress temporarily use New American Units during transition?
General consensus among archaeologists is that human life has its origins in the East African Rift Valley two million years ago. So no matter where you try to trace your ancestry from (whether you identify as Chinese, Czech, Chechen, Greek, Roman, Arab, Jew, Inca, or even Australian Aboriginal or American Indian) all humanoids ultimately emerged from a branch of primates from Africa. We are all descendants of our Paleolithic ancestors, ultimately quite African, having migrated prehistorically in successive waves to nearly every patch of habitable space on Earth. Humans have come a long way since we migrated out of Africa. No human is a foreigner when you consider Earth your home, so let us all use the same measurement system.