This is not a thing of the past, as any of you who have filled out a watch import form for US Customs well know; these duties are still levied. It's just that the margin on watches has gotten so fat that manufacturers don't care any more.

There was and is also an additional import duty on movements adjusted abroad, hence the prominent mention of 'Unadjusted' on many swiss movements destined for the US market, and a duty on watches cased abroad, particularly in precious metals.

: that many vintage watch movements have 17 jewels. This includes our
: beloved Heuer Chronomatic movements, also of note the Valjoux
: 22, 23, 71, 72, 92, 7734, 7736 & i'm certain there are more.

: Why 17 jewels ?

: Well there was a higher tax on watches with more than 17 jewels in
: the USA in the 1960's. I ran across this piece of information
: whilst reading an interesting listing on TZ-UK about the
: variants of the vintage Omega Seamaster 300 ( an iteresting read
: should you want to check it out
: http://forum.tz-uk.com/showthread.php?227473-A-Quick-Guide-The-Omega-Seamaster-300-including-Military-watches
: ).

: I wonder if this import tax classification influenced the initial
: design of the Cal.11/12/14/15 ?

: - Darren