The United States is one of just a handful of countries that that isn’t officially metric. Instead, Americans measure things our own way, in units that are basically inscrutable to non-Americans, nearly all of whom have been brought up in an all-metric environment. Most of the world uses meters, liters, and kilograms, not yards, gallons, and pounds. With so many industries and people crossing borders with so much fluidity, why has the U.S. not fully committed to the system the rest of the world uses? The answer is complicated.