[PeteVS]

My recollection is that GM started the negative ground thing because of corrosion or what ever and everybody else jumped on board when they all went to 12V. (I think that Packard stayed positive ground with the 12V changeover.)

Also, it was originally thought that elecTRICITY "flowed" from the positive post to the negative post. It was when Edison (or someone) put a plate in one of those new fangled light bulbs and tried putting a charge on it, they found out that elecTRONS would only flow in the opposite direction from what they had always assumed it should be. So, it turns out that ELECTRICITY flows in one direction, by definition, while the ELECTRONS are actually flowing the other way. The original thinkers had a 50-50 chance with the current flow way back when, and it turned out that they blew it. All of this, of course, is IMHO!