Sport: Head of the Horse Factory

Thoroughbred racing is described as the sport of kings. But the man who has sent far more winners to U.S. tracks than anyone in history has no blue — or even bluegrass — blood in his veins. He was born on Manhattan's Upper East Side and raised in Brooklyn. He cares less about equine lineage than about spotting a well-shaped colt with a cheap price tag.

Yet last week at Aqueduct, Trainer Hirsch Jacobs, 56, saw his 3,000th thoroughbred enter the winner's circle.

For two days Jacobs stood at 2,999 wins — and New York...