In North American auto racing, particularly with regard to NASCAR, a short track is a racetrack of less than one mile (1.6 km) in length. Short track racing, often associated with fairgrounds and similar venues, is where stock car racing first got off the back roads and into organized and regulated competition. Many traditional fans and purists still see short track racing as the "real" NASCAR, because the lower speeds make "paint swapping," where the bodies of the cars actually rub against one another, practical without a very high likelihood of serious accidents. In fact, NASCAR sanctions such "club" racing, offering the Whelen All-American Series as a national championship for the drivers, and an invitational race for club racers. In 2007, NASCAR is increasing marketing of the short tracks with the "NASCAR Home Tracks" campaign, with Greg Biffle, Elliott Sadler, and Carl Edwards featured in advertising to market short track racing. In some cases a Sprint Cup star or two will race in a weekly short-track event held usually on a short track near that week's race, or in a midweek special, such as the Slinger Nationals at Wisconsin's Slinger Super Speedway, a quarter-mile track (but is not NASCAR-sanctioned).