Dirt track racing is a type of auto racing

Auto racing

Auto racing is a motorsport involving the racing of cars for competition. It is one of the world's most watched televised sports.-The beginning of racing:...

 performed on oval tracks. It began in the United States before World War I and became widespread during the 1920s and 30s. Two different types of racecars predominated—open wheel racers in the Northeast and West and stock cars

Stock car racing

Stock car racing is a form of automobile racing found mainly in the United States, Canada, New Zealand, Great Britain, Brazil and Argentina. Traditionally, races are run on oval tracks measuring approximately in length...

 in the South. While open wheel racecars are purpose-built racing vehicles, stock cars (also known as fendered cars) can be either purpose-built racecars or street vehicles that have been modified to varying degrees.

Dirt track racing is the single most common form of auto racing in the United States.