The U.S. uses metric pretty much everywhere that is important, in most science, engineering, and medicine. Specific trades and common household things remain imperial due to inertia and no one really caring. It is much more accurate to say the U.S. has a dual system. We learn metric in school like everyone else.

Can't wait for us to adopt the metric Avogadro constant. I wonder what units they use for the Hubble constant in Europe (love me some megaparsecs).