No really, the worst thing that ever happened to metric system conversion was getting endorsed by the UN. That was the kiss of death. We created the UN, we host the UN, we fund the UN, and we hate the UN. Anything backed by the UN gets turned into the UN trying to take over the US and creating a new world order.

And after the debacle with the, UN-based, ITU trying to take over internet governance metric will never get a serious political foothold in the US.