Originally Posted by
LtKernelPanic
As for the metric system you'll probably never see that in the US namely due to the sheer number of road signs (distances between cities, mile posts, exit numbers, speed limits etc) that would have to be changed to KM. Add in reprinting of maps and the like and the cost would be astronomical.
A while back, California finally got exit numbers on their freeway signs. They didn't do a mass installation though--they only added the numbers as signs needed replacing/fixing. Might be something that could be done for metric conversion but it would take a fairly long while to fully complete.