K line O Scale model trains started in 1975 when the Founder Maury D Klein made the K line and offered it as a cheaper version of the Lionel brand. Maury was a dealer of Lionel trains and in 1975 brought out the first train to be named K line. He brought it out as an aftermarket train that would run on the same O Scale tracks as Lionel. Finally, in 2006 Lionel and MDK settled out of court and Kline had to file bankruptcy. A Chinese dealer of Lionel took over and he transferred the rights and intellectual property to Lionel.

K line has had a checkered past, but now Lionel's K Line O scale Model Trains are being sold again, legally and without distraction. Among collectors K line will always be thought of as a lower brand product. Lionel has now given the printing of post war era Lionel products. K line's budget trains are still the same as before, being a copy of the old Marx that a lot of Marx collector's are now taking Lionel K line parts for their trains. Lionel has finally come out ahead of its competitors and plans to stay there.