I was introduced to the metric system in the late 70s, in elementary school science class - it was the billed as the wave of the future. I'm guessing that wave kinda dissipated by the time it reached U.S. shores. Some metric units have creeped in, such as 2 liter soda bottles, nutritional value units, and computer capacity measurements, I'm guessing its because either those measurements didn't exist previously or no one paid attention to them. They tried selling milk by the liter, but that never caught on. We remain very much "imperial." And, personally, I hope they don't change in my lifetime, as feet, inches, and fractions thereof are second nature to me. Architectural specifications sometimes have both units, but I stopped including metric when typing them up myself.