Hat badges worn by NOPSI operating personnel: motormen, conductors, and bus operators.  Badge 239 is an example of the first badges issued by NOPSI in 1922.  It measures about 2½ by 2¼ inches, and is made of nickel-plated copper.  In the late 1930s, NOPSI began issuing badges like number 1004.  It measures about 2½ by 2 inches, and is stamped in aluminum.  Pictures are known dated during WW II showing both types of badges, so there must have been an overlap in their usage.  The aluminum badges are believed to have been in use up until the late 1960s.  The dates of use of badges of the type of number 1484 are not known to the author.  Information from knowledgeable readers would be most welcome.