Since its development in the mid-1940s, bluegrass music has become one of the most distinctive American musical forms, attracting an intense audience of supporters. A close cousin of country music (see entry under 1940s—Music in volume 3), bluegrass music is an acoustic musical style that features banjo, mandolin, guitar, double bass, fiddle, and harmony singing. Bluegrass is largely the creation of mandolin player, singer, and songwriter Bill Monroe (1911–1996). Monroe formed a band called the Blue Grass Boys in 1938. The band hired an impressive banjo player named Earl Scruggs (1924–) in 1945. Scruggs' up-tempo banjo-playing combined well with Monroe's distinctive mandolin playing and singing. Together, they created an entirely new sound in American music. Songs such as "I'm Going Back to Old Kentucky" and "Blue Moon of Kentucky" put them on the American musical map. Other musicians who imitated their style later gave that sound the name "bluegrass" in honor...