Almost all North American races are at a distance of one mile (1,609 m). Most races are run on tracks constructed solely for harness racing (some with banked turns), but a few tracks conduct both harness and Thoroughbred flat racing. North American harness horses earn a “mark” (a record), which is their fastest winning time at that distance. Harness races involve a good deal of strategy.
Though the vast majority of races are one mile, races are contested on several different size tracks. The most common are 1/2 mile, 5/8 mile, and 1 mile tracks. Certain horses are better on the smaller tracks and others are better on the 1 mile tracks because there are fewer turns. Also, on the shorter tracks early speed is important, while the longer stretch run of a mile track favors horses with late speed for come-from-behind wins.