Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Dirt track racing is a type of auto 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 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. There are hundreds of local and regional racetracks throughout the nation: some estimates range as high as 1500. The sport is popular in Australia and Canada also. Many of the cars may also race on asphalt short tracks during the racing season.