Back in the olden days, a good smooth riding horse was worth a lot of money. I think what is now the quarter horse started in Texas and was bred up as a working cow pony. They wanted them small because of the brush. When ranching went North up in snow country, they wanted bigger horses, so that is what they bred. What we have now does not resemble the old cow pony very much, and most never see a cow outside of the arena, if then. miles
The quarter horse started on the east coast and moved west with expansion. Quarter horse come in multiple sizes. My brothers breeds cutting type horse and they are typically shorter than racing breed horse. I mix my cutting breed with racing breed for more size and speed. I also have some racing bred mares.
https://en.m.wikipedia.org/wiki/American_Quarter_Horse#Breed_history
