West Coast Swing
As 'Swing' dancing became more popular, several of the original Lindy Hoppers moved to the west coast of the USA to work in the movies.
Due to focusing limitations of cameras at the time, and the desire to show many many syncronized dancers in the same scene, Lindy Hop evolved into a less circular dance, into one where the male lead stayed mostly in a fixed place while the female partner was led back and forth in a 'slot' or path (towards or away from the camera). The style also smoothed out - less athletic and more accessible to more conservative dancers.
Over time, the west coast swing has become a very smooth and popular dance, that can be danced to almost any form of popular music.