ATV
Unknown date, small size
Collection of the author

I believe this is the tenth ATV plate ever issued in Vermont; I also believe this is from 1984 or so. ATV plates started at 100A and went up from there.
April 1989, large size
Collection of the author

Eventually, plates were expanded to this format, which started at 100AT.
April 2001, large size
Collection of the author

Yet another format change, this time to AT0000. I think these went from AT1000 to AT9999.
July 2001, large size
Photographed in use

This 2001-dated plate was photographed in late 2006.

November 2008, large size
Collection of the author

Yet another format. My guess is that only AT100T to AT999T were issued, which is only a few hundred plates.

May 2008, large size
Collection of the author

This is the current ATV format. Not sure where these plates started - ATA100, perhaps?
May 2008, small size
Collection of the author

Plates switched from the larger size to the standard motorcycle plate size somewhere between ATF and ATG.
Undated, small size
Private ALPCA collection

Not sure if this is an error or a prototype - it should not be green!
February 2005, large size
Private ALPCA collection

This is a rare dealer type - never seen this one on the road. As you can see, the number is pretty low.