I teach a physics class, so I'm using both every day. I tell my students that when I was their age I seem to remember a push to make the US completely metric in a certain time span. I don't remember what the time span was, but it was back in the 70s when the movement started. Now it's 2009 and we've got 2 liter bottles of coke! Maybe in another 40 years we will have kilometers instead of miles. We are a stubborn group of people.

I have foreign exchange students who really don't understand why we are using such complicated measurements. Imperial to metric....easy! Metric to Imperial system...nightmare!