Wagering on sporting events is one of the oldest and most popular forms of gambling in the world. The ancient Romans gambled on chariot races, animal fights, and contests between gladiators. The Romans brought sports and gambling to Britain, where they have flourished for hundreds of years. Cockfighting, bear- and bullbaiting, wrestling, and footraces were popular sporting events for gambling throughout Europe during the sixteenth and seventeenth centuries. Horse races and boxing matches became popular spectator and betting sports during the eighteenth century. During the nineteenth and twentieth centuries, sporting events became more team-oriented and organized as rugby, soccer, and cricket grew in popularity.

Many early colonists in America brought their love of sports and gambling with them. Horse racing, in particular, became a part of American culture. However, the morals of the late eighteenth and early nineteenth centuries squelched popular support for legalized sports gambling. By 1910 almost all forms of gambling were illegal in the United States. This did not stop people from gambling on sports, however. The practice continued to flourish, and horse racing, in particular, managed to maintain some legal respectability as a betting sport.

Nevada legalized gambling again in 1931 and permitted sports wagering for a couple of decades. The influence of organized crime and sports gambling scandals led to a crackdown during the 1950s. Legal sports gambling did not return to Nevada until 1975, when it was tightly licensed and regulated.

Today sports gambling in the United States can be broken down into three primary categories. The first is pari-mutuel betting on horse and greyhound races and jai alai games. This form of gambling is legal in forty-three states. Although once quite popular, pari-mutuel betting has suffered a decline in recent years. The second form of sports gambling, permitted only in Nevada, is legal betting using a bookmaker. The third and most widespread form of sports gambling is illegal betting.