Twelve-bar blues became the most common current structure of blues music in the first decades of the 20th century.
 The blues scale is ubiquitous in modern popular music and informs many modal frames, especially the ladder of thirds used in rock music (for example, in "A Hard Day's Night")
The musical forms and styles that are now considered the blues as well as modern country music arose in the same regions of the southern United States during the 19th century

