Delirium said:
Miles are still used in both the United States and UK, which between them count for a pretty large proportion of the English-speaking world.
In the UK this is only for "folk" uses such as pints of beer and road signs. I believe all scientific and engineering ventures switched to SI long ago, and nearly all commercial institutions (aforementioned pints of beer excluded, for instance) are required to use metric measure although they are also permitted to provide equivalent ounces, pounds, stones and whatnot. They sell orange juice in liters, butter by the kilogram, cloth by the meter. Liquor is sold in metric measure, so in a pub you get a pint of beer but a 35 ml measure of brandy, and a 200ml glass of wine.
Road signs haven't switched because it would be very difficult and dangerous as well as politically explosive.