Barbershop harmony is one of only a few forms of music that is native to the United States. Its evolution was similar to other forms of vocal music. The barbershop style comes from the combination of chord structure, sound, delivery and interpretation, which locks the chords to produce overtones. In the early years of American barbershop music, singers usually improvised the harmonies, or "woodshedded."

This particular style of music emerged in the mid nineteenth century as part of the minstrel and vaudeville shows. At the turn of the century, amateur singers, usually men, could often be found woodshedding at gatherings. Minstrel shows also featured quartets, which sang as an "olio" act while the next performer prepared for his presentation.

Growth was encouraged by the types of songs popular between the 1860s and 1920s, songs characterized by sentimental lyrics and uncomplicated melodies that could be harmonized with a variety of four-part chords. It appeared at a time when the barbershop was a social center of many communities. The men’s barbershop organization, the Society for the Preservation and Encouragement of Barber Shop Quartet Singing in America (SPEBSQSA) was formed in 1938. Sweet Adelines, Inc. was founded in 1945.

In 1991, Sweet Adelines, Inc. changed its name to reflect its motto, "Harmonize the World." The organization became known as Sweet Adelines International and truly is an international organization, with more than 30,000 members in more than 650 choruses and 33 regions in the United States, Australia, Canada, Finland, Germany, Japan, the Netherlands, New Zealand, Sweden and the United Kingdom.