How to I.D. plates by design?

[Guest sofasurfer]

I have some old photos from the 30s and 40s. I want to ID the year the pic were taken by the plates on the cars in the photos. The plates are not readable but the design pattern, or layout of the numbers and letters is visible. These are Michigan photos and so I found this website... License Plates by the Year Exhibit - Michigan Historical Museum ...which shows pictures of plates of all years. Well, I thought I had it figured out until I found a photo in which the plates are all readable. In that photo there are 4 different plate layouts, all from 1939. I have included a picture showing the plates. My question is, why are there so many different plate designs, which do not appear on the above mentioned website) and is there a website where I can find all of the different designs to be able to ID plates by design?

And one more question. Is it possible to research who owned a vehicle from the plate number, decades ago?

Edited December 23, 2010 by sofasurfer (see edit history)

[Larry Schramm]

Looking at the top two plates, I believe that they are commercial plates, possibly for a trailer because they have an expiration date. There are no car plates that I can remember from Mich that have an expiration date on it and that goes back to at least the 50's. The letter/number sequence usually identified as a car or a commercial truck until maybe the 90's.

[Jim Rohn]

the top two plates are clearly for a passenger vehicle as they say PASS

they are partial year plates

they were common through the early 60's IIRC

the size differences were many until 1957 when all the states came up with a "standard" size plate

Edited January 1, 2011 by Jim Rohn (see edit history)