Digital BW, The Print

It is not really US vs Europe. It is North America vs. the rest of 
the world. But that's not the point here :-).

I used to work for Philips USA, and it was always a pain printing 
out word documents from HQ and having the page numbers all be off. I 
finally started just making a pdf and printing that instead.

Don't know dates, but the A2, A3, etc. sizes are designed to have 
the same aspect ratio, so you can resize documents without having to 
reformat your word document (or leave blank space etc.). There is 
also supposed to be some psychological basis for the aspect ration 
chosen, but don't remember the details. 

A2, A3, etc. are part of the metric system, which means the US will 
never convert :-).

Note that 8.5x11 was not officially standard until the 80s, which 
would have been a good opportunity to convert. Of course, it was 
unofficially the standard, so it probably would have been too 
painful to convert. 

Manoj