The U.S. Customary System is dated and needs to be replaced. It's roots are British and they don't use it anymore. As of 1866, it was deemed lawful to use metric units, but we need to switch our economy to back this change. Yes, this switch in mindset will not be smooth or easy, but give me any other legitimate reason that we shouldn't make the switch. There are three countries in the world that use the U.S. Customary System. Only one of those, the United States of America, is industrialized. The U.S. Customary System has become obsolete and we need to make it so.
Further breakdown: http://www.zmescience.com/other/map-of-countries-officially-not-using-th...