Here’s a map of all of the countries in the world that still use pounds as their primary unit of weight:
And here’s a map of all of the countries that don’t:
That’s right – pounds are used by Liberia, Myanmar, and popular space-faring nation The United States of America. And by no-one else AT ALL.
And here’s why you should care. In September 1999, NASA lost itsMars Climate Orbiter craft, ruining a mission that cost over 655 million dollars. The reason for this loss? One part of the Orbiter calculated propulsion in the Imperial system of pound-seconds of thrust, whereas another part used the international standard metric system of newton-seconds of thrust. This caused the Orbiter to gradually deviate from its intended trajectory, and disintegrate in the Mars atmosphere. (And the bit that worked in pound-seconds wasn’t made in Liberia or Myanmar.)