Slot cars and the tracks they run on were first manufactured by Lionel, best known throughout the 20th century for its electric train sets. In fact, Lionel first offered slot cars in 1912 that were powered by trough or slot set between the rails. Lionel, however, dropped the racing car line when its train sets proved much more profitable. Slot cars appeared in toy stores occasionally for several decades, but they really became popular in the 1960s when Aurora, the scale-model kit manufacturer, secured the U.S. license for British-made Playcraft Model Motoring slot cars in an HO scale. Aurora sold 25 million slot cars in five years. Within six years, more that 3,000 commercial slot tracks were built in toy stores and hobby shops throughout the United States where kids paid two bucks to race their cars for an hour on intricate, fast tracks. The slot car craze was pretty much spent by in the late 1960s.