The most popular horse breed in the world is the Thoroughbred**. This is due to their versatility in racing, show jumping, and other equestrian disciplines.
However, the Quarter Horse is very popular in the United States, particularly for its athleticism, speed, and calm temperament. It is well-suited for various activities like:
* Rodeo events
* Western riding
* Ranch work
* Trail riding
While it's not the most popular breed globally, the Quarter Horse is definitely a top contender for the title of most popular breed in the United States.