Blues is a music genre which was originated in the Deep South of the United States around the 1870s by African Americans from roots in African musical traditions, African-American work songs, and spirituals. Blues incorporated field hollers, shouts, chants, and rhymed simple narrative ballads.The blues form, ubiquitous in jazz, rhythm and blues and rock and roll, is characterized by the call-and-response pattern, the blues scale and specific chord progressions. Blues shuffles or walking bass reinforce the trance-like rhythm and form a repetitive effect known as the groove.

Robert Johnson – “Me and the Devil Blues”

Early blues frequently took the form of a loose narrative, often relating the racial discrimination and other challenges experienced by African-Americans.

The blues are a song of abandonment and despair, but they’re also a kind of euphoria, a freedom cry of survivorship and deliverance down the open road. The blues are about poverty and bottom-of-the-barrel hard times.

Lead Belly – “Bourgeois Blues”

The long boom following World War II induced another massive migration of the African-American population, the Second Great Migration, which was accompanied by a significant increase of the real income of the urban blacks.  Naturally, the blues both went with those people and was left behind. Race records were 78-rpm phonograph records marketed to African Americans between the 1920s and 1940s. They primarily contained race music, comprising various African-American musical genres, including blues, jazz, and gospel music. Before race records, you had to be where blues music was, meaning its audiences were local or regional at best.The use of widely distributed race records effectively kicked off the blues as a national commodity.

In the 1950s, blues had a huge influence on mainstream American popular music. While popular musicians like Bo Diddley and Chuck Berry, both recording for Chess, were influenced by the Chicago blues, their enthusiastic playing styles departed from the melancholy aspects of blues.

B. B. King – “Chains and Things”