European speed limit signs are circular. Can maybe introduce them by having the round kph set up on the same stalk as the mph signs for a couple of years, then gradually remove the square mph signs…
I should think that replacing the mile markers on the interstate system would be the much bigger pain, as well as renumbering all the exits, etc., but hey, it did take awhile to build the stuff…
heh heh…“How’s my Driving?”