Jose Santos Jr.

Unless you are riding in the very best races for the best stables, it's not easy being a jockey in Great Britain. Prize money in the bread-and-butter races is dreadful and, even in these lower-level events, the competition for mounts can be fierce. Four years into her career, 22-year-old jockey Grace McEntee had had enough. In search of a better life, she booked a one-way ticket to Kentucky and will begin the next stage of her career Saturday at Turfway Park when she makes her U.S. debut. "This is very...