Interestingly, gaited horses were apparently quite common in the middle ages in Britain. Before there were real roads, you traveled on horseback (or on foot). Not coaches. There would be farm wagons but they were rough and slow.
The wonderful recent thread here on COTH on the history of royal coaches pointed out that the first ceremonial coaches were built in the 1600s and suspension came along later. The big era of long haul commercial coaching started in the 1700s and ends by 185O with the creation of railroads. Fox hunting with jumping emerges as a sport after 1800 as the countryside is more and more fenced. TB breeding and racing gets consolidated over the 1700s. So I think there’s a change in horse usage from wanting gaited amblers to horses with big carriage trots or big canter gallop for hunting and racing.
In the US, the gaited breeds really emerge out of the plantation economy in the South pre civil war, where plantation owners and overseers needed to ride miles over land without roads and through fields. I expect they were able to build on older strains of gaited horses from Britain. And those plantations could be huge
The Spanish descended horses don’t typically gait, and it doesn’t really correlate with the attributes you need to work cattle in either Spanish or American style. So it doesn’t tend to turn up in Mustangs historically.
The Morgans come out of a Northern small family farm environment.
I get the impression that the South used a lot of mules as draft animals, like plowing, rather than big draft horses. Also I’m not sure of the cultivation cycle for the big Southern export crops of cotton, tobacco, and sugar originally. They may not need plowing in the same cycle as Northern grain crops. Rice definitely doesn’t. Whereas wheat on a large scale needs plowing sowing harvesting all done with horses and equipment.
Ok. Up to now I have given no thought at all to farming practices and their effect on regional breeds of horses
But my point was the gaited horses go way back to middle ages in Anglophone culture.