The blues is an American musical form that draws from numerous older musical traditions. A product of America's cultural melting pot, it originated in the American South before spreading and evolving to other parts of the country and around the world.

Early History
In the early 20th century, the blues came into being at the historical moment when the recording industry was being established. Blues itself originated in isolated rural communities of the Mississippi River Delta, where mostly black musicians combined African rhythms and instrumentation with American folk themes and elements of gospel music. Blues recordings were some of the earliest popular records sold in the United States, thus distributing the blues far and wide and making it accessible to many new musicians who would eventually contribute to its growth.

Later History
Following the end of the Great Depression and World War II, Americans began to flock to the cities in a wave of urbanization. Many Southerners left agricultural jobs to work in industry in places like Memphis, Kansas City, and Chicago, and they took their blues traditions with them. While Delta Blues remained a distinguishable musical style, new schools of blues arose in each of these cities. With the invention of the electric guitar and bass, blues music took on a new character as played by a younger generation of musicians.

Key Figures
Blues music was originated by many different performers, some of whom never recorded their music and are no longer known. As blues music gained the appreciation of scholars and music historians, many of these original performers (some of them in their seventies and eighties) were tracked down and asked to share their music by recording for the first time. Robert Johnson may be the best known blues musician of all. His series of recordings from the 1930s epitomize the style of blues when the genre was established but had yet to begin its varied evolution. Other important musicians in the development of blues include Blind Lemon Jefferson and Lonnie Johnson.

Cultural Origins
The Atlantic slave trade was responsible for bringing many of the elements necessary for the origination of blues music to one place. African music, with its string instruments and exaggerated singing style, became the basis of the blues. To this, the first blues musicians added elements of Christian gospel music that was taught throughout the South, both before and after the Civil War. Field chants, which originated with slaves and carried over to the agricultural laborers in the 19th and 20th centuries, also supplied much of the musical history for the blues.

Blues Themes
In the 1910s, the term "blues" was first used to refer to the sadness of many notable blues songs. Issues of death, failed relationships, and poverty are common in blues from this era. The oppression of workers and natural disasters (especially those that threaten agricultural production) are also at the center of many blues songs. For example, a series of disastrous floods in the 1920s were turned into blues songs by musicians who saw their communities struggle to deal with the loss of crops and homes. Racism and the legacy of slavery also figured prominently in the thematic origins of blues music.