I didn't know that it was required. My father's childhood bike has a town issued liscence plate as identification in case of theft. I think (haven't seen it for months) the Sturmey hub is dated 62.
What you could perhaps find are so-called 'moped' plates. We had those little insurance tags up to '05 I think, and switched to proper license plates with insurance papers for mopeds after that. They are the perfect size to put on a bike, about 4 by 4 inch...
Love reading all these replies about an aspect of bicycle history. Would be a good subject for a book, there must be thousands of plates that still exist. http://www.flickr.com/search/?page=2&q= ... t=3&page=3 that link is page 3 of a list, if you click on page 4 there is a Calgary 1982-1983 which was their last issue plate.
My hometown of Ridgewood, NJ, used the metal plates thru 1978. They were registered at the Police Dept. My 1st city license was '79, when it became a decal. Plenty of vintage plates on ebay! Apparently, Johnstown, PA made a ridiculous amount of them, as they show up most frequently!! ~Adam