Infinity focus - have we got it wrong?

In Australia we've used metric units for a long time, but when we did use "Imperial" units (I'm sure you wouldn't call it that in the US), for 1/1000th of an inch we usually used the term "thou" (short for "thousandth"). Is "thou" used at all in the US?

http://en.wikipedia.org/wiki/Thou_%28length%29

Actually, if I see "mil" I assume you're referring to 1/1000 of a metre i.e. 1mm.

http://en.wikipedia.org/wiki/Millimetre

When it comes to a millionth of an inch do you guys just give up and use the metric unit instead: micrometer/micrometre/micron/µ?

http://en.wikipedia.org/wiki/Micrometre

I presume in US science that metric is the predominant measurement system, but what about in US engineering?

Dan.