Oval track racing is a form of closed-circuit motorsport that is contested on an oval-shaped race track. An oval track differs from a road course in that the layout resembles an oval with turns in only one direction, and the direction of traffic is almost universally counter-clockwise. Oval tracks are dedicated motorsport circuits, used predominantly in the United States. They often have banked turns and some, despite the name, are not precisely oval, and the shape of the track can vary. Major forms of oval track racing include stock car racing, open-wheel racing, sprint car racing, modified car racing, midget car racing and dirt track motorcycles. Oval track racing is the predominant form of auto racing in the United States. According to the 2013 National Speedway Directory, the total number of oval tracks, drag strips and road courses in the United States is 1,262, with 901 of those being oval tracks and 683 of those being dirt tracks. Among the most famous oval tracks in North America are the Indianapolis Motor Speedway, Daytona International Speedway and Talladega Superspeedway. Oval racing Pack racing Pack racing is a phenomenon found on fast, high-banked superspeedways. It occurs when the vehicles racing are cornering at their limit of aerodynamic drag, but within their limit of traction. This allows drivers to race around the track constantly at wide open throttle. Since the vehicles are within their limit of traction, drafting through corners will not hinder a vehicle's performance. As cars running together are faster than cars running individually, all cars in the field will draft each other simultaneously in one large pack. In stock car racing this is often referred to as "restrictor plate racing" because NASCAR mandates that each car on its two longest high-banked ovals, Talladega and Daytona, use an air restrictor to reduce horsepower. The results of pack racing may vary. As drivers are forced to race in a confined space, overtaking is very common as vehicles may travel two and three abreast. This forces drivers to use strong mental discipline in negotiating traffic. There are drawbacks, however. Should an accident occur at the front of the pack, the results could block the track in a short amount of time. This leaves drivers at the back of the pack with little time to react and little room to maneuver. The results are often catastrophic as numerous cars may be destroyed in a