North American turf racing was mainly confined to steeple chasing and hurdlers in the early part of the nineteenth century, with only a handful of tracks running turf races on the flat, and even then, often only one race per day.  Through much of that time there were only a handful of stakes races available as races on dirt dominated.  The Washington D.C. International Championship, an invitational with some of the leading turf horses from around the world invited to compete, was the forerunner of what was to come.  Soon, the New York Racing Association (NYRA) got in on the act with such races as the Man o’ War and New Jersey with Its United Nations Handicap.  Back then, there were few big races for fillies and mares, and in order for them to compete on the grass, they had to go up against males.  At first, trainers and owners were hesitant about competing against males, but as the years passed by, more races for fillies and mares only were introduced, and these same owners and trainers began to take interest.  In the late 1960s, turf racing for fillies and mares became more common, and by the mid to late 1970s, with great mares such as Dahlia and All Along making the trek across the Atlantic, it became immensely popular.

Following is HorseRacing20thCentury99.com’s list of the top ten fillies or mares to have raced on turf in North America during the twentieth century.  You will notice that these fillies and/or mares also ran against males during their careers and, in some cases, proved superior.  However, I also feel that they should have their own list separate from males.  I have allowed fillies and mares from other countries to be included with the only criterion that they race at least once in America.