Bluegrass is a distinctly American form of music that developed out of country music during the late 1930s and throughout the 1940s. It originated when country singer and songwriter Bill Monroe (1911–1996) altered the tempo, key, pitch, and instrumentation of traditional country music to create a new style. A native of Kentucky—known as the bluegrass state—he named the style after his own band, the Blue Grass Boys. In October of 1939 Monroe and his band appeared on The Grand Ole Opry radio show and performed this new style of music. Although bluegrass has changed since those days, Bill Monroe remains the "Father of Bluegrass."
Further Information: Brown, Charles. Music USA: America's Country and Western Music. Englewood Cliffs, N.J.: Prentice Hall, 1985; Hemphill, Paul. The Nashville Sound. New York: Simon and Schuster, 1970; Planet Bluegrass. [Online] Available http://www.bluegrass.com, October 23, 2000.