The APHA was started, to register those foals that had a little bit too much white on them. The AQHA had rules on how high stockings could be, bald faces, spots etc. The foals that had too much white,and were purebred QH's were called "crop outs".
Thanks. I've read that in the rule book, but couldn't remember the particulars. That's why a Quarter Horse can be registered with both the AQHA and the APHA but a paint can only be registered with the APHA.
That's the reason in a nutshell but there is lots more to it. In the early 1960's there were two paint horse associations, the American Paint Stock Horse Association and the American Paint Quarter Horse Association. They merged to form the American Paint Horse Association.
Lots of interesting reading, if you like paints, in the books "The American Paint Horse" by Glynn W. Haynes and the book that the paint horse association puts out called "The American Paint Horse, A Photographic Portrayal".
This is interesting:
Several years ago a Paint Horse that resulted from the mating of two registered Quarter Horses was an outcast because he could not be registered in their association. The authenticity of the breeding was also questioned by some horsemen who did not understand that a few of their finest horses carried recessive paint genes, and sporadically the action of these genes was exhibited in one of the foals. The Paint crop-outs were usually gelded, sold or disposed of to avoid embarrassment to the owner and futile explanations. It made no difference what names could be found in their pedigrees; they were of little value to their owner, and their selling prices were no more than those of good-grade stock horses.