A bit of info on the metric system and metrication

The three remaining non-metric countries (but see below for more information on that)

Here's a piece in the Baltimore Sun from last month about a complete switch over (not just officially but as a people too) to the metric system:

Why is the English system confusing? Well, for one, you can measure length in inches, feet, yards, miles, furlongs, spans and leagues. But it's not as if these units are related in any concrete, sensible way. Everyone knows there are 12 inches in a foot, but how many feet are in a furlong?

Quickly now, what is your answer?

Wrong! A furlong is 660 feet, or one-eighth of a mile. Don't feel bad. A recent Janet's World study of Maryland high school science teachers reveals that they largely ignore the English system except at the grocery store, where they are forced to purchase their milk in gallon increments and an occasional box of "Fruit by the Foot" for their children.

and:

But back to my school days. After the two-month elementary school unit on the English system, the metric system, or "SI" (Système International) was introduced. It took about a quarter of an hour. But this is only because it made perfect sense.

The next one is from 2005 and I noticed it on the Wikipedia page on metrication as it was added there last month as a reference. You'll notice on the map above that only the United States, Liberia and Myanmar are still not using the metric system, but this page says that in practice it has already pretty much taken hold:

From time to time there is a discussion about which nations of the world are yet to 'Go metric'. These always involve the USA and usually two others, most often Liberia and Myanmar (Burma).

However, this discussion often ignores a basic truth.

The reality is that all nations in the world, including Liberia, Myanmar, and the USA, are on the pathway to full metrication but they are at differing points along this path. For example, Liberia and Myanmar are both substantially metric countries that trade internationally in metric units. Visitors to these places report that they also use metric units for most things internally with only a few exceptions like old (ancient) petrol pumps calibrated in British Imperial gallons.