The ability to offer lower fares, for flights within and to/from the US, was restricted by the then Civil Aeronautics Board, formed in 1938 and operative since 1940. Originally the CAB only allowed a single fare to be charged for a flight, but after they started to slowly allow different fares in 1952, the airlines first offered different fare levels but still in one cabin style, and then in 1955, TWA came up with the concept of different service standards for the different fares. This marked the start of two-class planes, with the better class generally called First Class and the worse class originally, in the US, being termed Coach Class.[1]