there was a list in EASYRIDERS mag a while back. it was a pretty long list.
if i remember it aslo had the dates the maunufatures were in business.
and if they made other stuff when they started or stopped making motorcycles.
a lot of motorcycles sprung from bicycle companies(schwinn dabbled in motorcycles for awhile)
i know i dont have that issue(someone put it in the bathroom at work), but maybe someone has it and can dig it up.
I have a book on american motorcycles and there was more than 100 manufacturers in there from the early 1900's on.
The war effort killed most of them off as they where repurposed to build war machines and stuff.
Which is what happened to crocker.
Here's a source I've had kicking around forever. Sorry about the photo quality. The 2nd photo is of the last page of the book - 480 pages. The 3rd photo is a typical page in the middle of the book - photo(s), details. The 4th photo is from the back - there are a bunch of pages in the back with very brief mentions of lotsa manufacturers. Some only get a sentence. Dunno the total number of manufacturers mentioned.