I'm actually reading a book on this debate right now, "Meter Means Measure - the story of the metric system"
Apparently one of the first congressional lobbies was one formed by industry giants in the late 1800s to squash a metric bill proposed and originally supported by most of congress. After the lobby was formed against it, Alexander Graham Bell came to speak before Congress, explaining in context his experimentation (with flight, not the phone) that converting between complex measurements of thrust, mass, and volume he found it easier to first convert measurements to metric and then to use metric measurements throughout the rest of his design and problem solving. In addition, he taught the laymen at his shop with no prior knowledge of metric what to do and they picked up on things quite handily, and liked it.
I think he should have made the, "It's more patriotic to stick with the British system!!!" argument - my favorite.
P.S. Although I am in favor of adopting SI units, I will never adopt British spellings - Favourite, Tyres, Neighbour. I can't deal with them
