Which early style of blues used harmonica?

The early style of blues that prominently featured the harmonica is known as "Delta blues." Originating in the Mississippi Delta region, this genre often combined the harmonica with guitar to create a raw, expressive sound. Notable artists like Son House and Charley Patton utilized the harmonica to convey deep emotion and storytelling within their music. This style laid the groundwork for various blues and rock genres that followed.