The street balladry of the people who began migrating to America in the early 1600s is considered to be the roots of traditional American music. As the early Jamestown settlers began to spread out into the Carolinas, Tennessee, Kentucky and the Virginias, they composed new songs about day-to-day life experiences in the new land. Since most of these people lived in rural areas, the songs reflected life on the farm or in the hills and this type of music was called "mountain music" or "country music."

The invention of the phonograph and the onset of the radio in the early 1900s brought this old-time music out of the rural Southern mountains to people all over the United States. Good singing became a more important part of country music. Singing stars like Jimmie Rodgers, family bands like the Carter family from Virginia and duet teams like the Monroe Brothers from Kentucky contributed greatly to the advancement of traditional country music.

The Monroe Brothers were one of the most popular duet teams of the 1920s and into the 1930s. Charlie played the guitar, Bill played the mandolin and they sang duets in harmony. When the brothers split up as a team in 1938, both went on to form their own bands. Since Bill was a native of Kentucky, the Bluegrass State, he decided to call his band "Bill Monroe and the Blue Grass Boys," and this band sound birthed a new form of country music.

"Bill Monroe and the Blue Grass Boys" first appeared on the Grand Ole Opry in 1939 and soon became one of the most popular touring bands out of Nashville's WSM studios. Bill's new band was different from other traditional country music bands of the time because of its hard driving and powerful sound, utilizing traditional acoustic instruments and featuring highly distinctive vocal harmonies. This music incorporated songs and rhythms from string band, gospel (black and white), work songs and "shouts" of black laborers, country and blues music repertoires. Vocal selections included duet, trio and quartet harmony singing in addition to Bill's powerful "high lonesome" solo lead singing. After experimenting with various instrumental combinations, Bill settled on mandolin, banjo, fiddle, guitar and bass as the format for his band.