It's amazing what you can learn on Jeopardy. There are only three countries in the world that don't officially use the metric system ... one of them (naturally) is the United States. I do recall at one time the U.S. was very close to converting (they even put dual metric / English measurements on car speedometers), but they never followed through.
It shows how far behind the U.S. is when you consider the only other two countries that don't use the metric system: Myanmar and Liberia. Hardly two world powers. Of course, the U.S. always goes its own way.