Where is this 1922 plate from?   Is it indeed from Mexico, but long believed.  But no one has definitive proof and there have been many questions.  For examples, the surviving examples (at least two are known) are all five digits long, which seemed very high.  It must be from Mexico City, but the “M de M” legend didn’t fit any known early issues for Ciudad de Mexico or Distrito Federal  For many years, this plate has been a mystery for license plate historians and collectors.  Long believed to be from Mexico, but

This photo shows another crowded avenue, presumed to be in Mexico City.