Need some help with the history of Pocket bikes

Hi Guys and gals, I am trying to put together information for an article on Pocket bike Racing.

Some information I need assistance with is:

How long have pocket bikes been around world wide and who was the first to produce them?

When did they first arrive in the US and what were the manufacturers?

When did they start becomming so popular in the US?

Thanks everyone for all your help.
Mitch

not all of your answers but I have seen Dandy pocket bikes from as far back as the 1970s and one of my customers remembers seeing the first pocket bike in the US used at the 1981 Formula One Grand Prix of Detroit, it was used as a pit bike for one of the teams. That is obviously not the first sighting just the first time he saw one and that dates back quite some time so unless someone knows of an earlier time you can use that as one of the first sightings.