Why are there so few horse races at 1 1/4 miles (10 furlongs) in the USA?

You're correct. A horse’s fitness plan must be coordinated properly in order to prevent injury or unnecessary lameness, note that we have numerous injuries due to horses running too early in age, while some can others can't, so instead of doing this the industry had amended race length. Sprinting exercises in most cases are appropriate for training two-year-old racehorses, but they are mentally incapable of handling too many of them. What I know is that a horse’s skeletal system adapts to the exercise they are receiving. Because the skeletal system does not reach full maturity until the horse is at least four years of age, young racehorses often suffer multiple injuries so they feel by cutting back furlongs will help this cause. Bottom line it's a band-aid not a solution. Also, owners are retiring horses to stud way too young these days, .. with some to most who haven’t had a chance to mature. As stated all thoroughbreds can be raced young, other than a few exceptions. Most horses need a little more time to develop.. the proof is in injuries, which are too numerous these days...with 2 and 3 year olds being most vulnerable. An example would be Zenyatta, she set an example to prove that thoroughbreds can start racing at an older age and be successful..All we can do is voice our opinions with strong fact based reasons and hope for change, and then we can incorporate appropriate longer races....

:)

Win: (5) Game on Dude Place: (2) Flat Out Show: (9) Ron the Greek Alternate: (4) Fort Larned Alternate 2: (11) Mucho Macho Man

IMO, it's because nowadays, U.S. horses are bred to mature and run early. That's what the commercial market demands. Most owners want to see some return on their investments as soon as possible. Precocious horses tend to be sprinters and middle distance horses, It takes a patient, and well off, owner to take the time to allow a classic-distance horse to mature. Training is also a factor. I don't think American trainers are as good at physical conditioning as their European counterparts. Finally, as there are fewer classic-type horses, there's less demand for classic-distance races. This leads to races being shortened. A lot of stakes races that used to be 10f or longer have been reduced in length.