The origins of the harmonica are obscure, but it seems to have appeared first in Germany. There several tinkerers devised instruments based on the the fact that air blown over a reed fixed at one end but floating free at the other produces a note that can be tuned according to the length and thickness of the reed. By putting several reeds side by side and tuning them to the scale, one can create a musical instrument.

Around the beginning of the last century, Christian Friedrich Buschmann, an early maker, wrote his brother that he had invented "a new instrument that is truly remarkable. In its entirety it measures but four inches in diameter but gives me twenty-one notes, all the pianissimos and crescendos one could want without a keyboard, harmonies of six tones, and the ability to hold a note as long as one would wish to."

A few years later, a Bohemian inventor named Joseph Richter improved on Buschmann's idea by adding a second row of reeds above the first but oriented in the opposite direction. Under this arrangement the notes of the bottom row sounded as the player blew air out, and the upper notes sounded when the breath was drawn in.

By the time Matthias Hohner came along, the basic form of the harmonica had already been set. Hohner actually was more an entrepreneur than an inventor. His most distinctive contribution to the instrument's development were the ornately engraved cover plates bearing the company name. Still, he put his considerable talents of salesmanship and promotion to work, improving production and buying up competitors.

Hohner introduced his first harmonica to America in 1862.  Hohner cleverly exploited the prestige of well-known musical figures to enhance the appeal of his instruments. The Marine Band model, which became the most popular harmonica of all time, was named after the famous band led by American bandmaster John Philip Sousa.

Sousa himself was persuaded to endorse the Hohner harmonica in a statement printed on the instrument box and reproduced in advertisements across the country. "This instrument is a foundation for a musical career," Sousa said, "and many boys and girls who are now learning music on the harmonica will step into the great symphony orchestras and bands of our country some day."

Sousa may have been exaggerating, but during the Depression of the 1930s more than 2,000 harmonica bands were formed to give young people musical training. As a tribute to the groups, Sousa composed a rousing march entitled "The Harmonica Wizard."

By the time Hohner died in 1902, his name had become virtually synonymous with "harmonica." From an original staff of one in 1857, the Hohner company grew to 3,000 employees in 1913, who produced 10 million instruments that year. By the 1920s, sales had grown to 25 million instruments a year.