High Quality Content by WIKIPEDIA articles! The AMA Grand National Championship is an American motorcycle racing series. The race series, founded and sanctioned by the American Motorcyclist Association (AMA) in 1954, originally encompassed five distinct forms of competitions including; mile dirt track races, half-mile, short-track, TT steeplechase and road races. Also known as flat track racing, the championship was the premier motorcycle racing series in the United States from the 1950s up until the late 1970s when, supercross events held in easily accessible major league stadiums became more popular.