Straying seriously off-topic here, but hey, Jeff started it...
The engine in my car was built in Canada, and the car was assembled in the USA. Everything under the hood is NOT metric; in fact, changing the alternator requires a 9/16" wrench to loosen the part and a 10mm wrench to loosen the belt...both bolts running through the same chunk of steel. The United States continues to use its non-metric measurement system because there is no compelling reason to make wholesale change, and many compelling reasons NOT to. The result is that we have a mixed system here. Where it is appropriate or necessary to do so, Metric measurements are used (usually when international trade is involved) and otherwise US measurements are used. Agencies which have attempted to do wholesale conversion have found that it is simply not practical and too expensive. For instance, for a while, the Ohio Department of Transportation speced all bridge projects in Metric. That lasted about two years before they switched back.
In this country, the entire infrastructure is built in feet, inches, ounces, and pounds...thermometers, scales, gas pumps, lumber, and more. If there were a compelling reason to junk everything and start over with new numbers, it would happen. But for the moment, the compelling reason does not exist. Certainly, more and more bits of our country will slowly convert over, but it is going to take a very long time.
--Dave Althoff, Jr.
Who notes that while his last video camera used 8mm tape, the one he just bought uses 1/4" tape...