A major attraction of the Cumberland County Fair is harness racing 10 times over the seven day fair. It carries on a racing tradition from 1871 when the fair was first held and farmers raced horses on Maine Street in Cumberland.

Harness racing is a form of horse racing in which the horses race at a specific gait (a trot or a pace). They usually pull a two-wheeled cart called a sulky. In North America harness races are restricted to Standardbred horses, although European racehorses may also be French trotters or Russian trotters, or have mixed ancestry with lineages from multiple breeds. Orlov trotters race separately in Russia. The light cold-blooded Coldblood trotters and Finnhorses race separately in Finland, Norway and Sweden.

Standardbreds are so named because in the early years of the Standardbred stud book, only horses who could trot or pace a mile in a standard time (or whose progeny could do so) of no more than 2 minutes, 30 seconds were admitted to the book.[1] Today, most harness races are won by Standardbreds who post times of 2 minutes or less.[citation needed] The horses have proportionally shorter legs than Thoroughbreds, and longer bodies.[2] Standardbreds generally have a more placid disposition, due to the admixture of non-Thoroughbred blood in the breed.