The US will switch to metric when we have 10 months in a year, 10 days in a week, 100 (or 1000) days in a year, 10 hours in a day, and 100 seconds in a minute.

The US will switch to metric when we have 10 months in a year, 10 days in a week, 100 (or 1000) days in a year, 10 hours in a day, and 100 seconds in a minute. Seriously, one thing that I've realized living in a country where metric went over like a loud fart in church is that metric only works when units are arbitrary; but many times we need to measure things that are not arbitrary.