Final answer:
The earliest known blues styles were known as Delta blues, originating in the rural South and characterized by syncopated rhythms and 'blue' notes, deeply influencing various music genres.
Step-by-step explanation:
The earliest known blues styles were called Delta blues because of their origins in rural areas of the United States, particularly the South. These styles were deeply rooted in African-American history, reflecting the life and struggles of the black community through both themes and musical composition.
Delta blues laid the foundation for what would become defining elements of not only blues but also other genres like jazz, rock n' roll, and gospel. These influences are particularly apparent in their use of syncopated rhythms and "blue" notes, which became hallmarks of African-American music.