On Fri, 28 May 2010 21:02:27 -0400, Patrick Finnegan <pat at 
computer-refuge.org
  wrote: 
  km signs indeed do exist.  I-19 from Tuscon, AZ south
to the Mexico
 border is an example.. distances and exit numbers are given in km.  I
 can't remember for sure if speed limits are give in km/h at all, but I
 think they aren't.
 Pat
 --  
They were for a while (mph and kph) until someone beat a speeding
ticket claiming that he mistook the kph posting to be mph...
        CRC