In terms of body shape, bracing, and decorative inlay designs of the instruments, all manufacturers have been directly or indirectly influenced by the designs of Christian Frederik Martin (1796 - 1873). In the 1920s and 1930s, the Martin company introduced many significant changes. Gut strings were replaced with steel strings. To absorb the greater tension of the strings, the bracing system was additionally reinforced on the body and the top of the guitar. Pulling the neck out of the body allowed for comfortable playing in the higher frets. In a typical steel-strung acoustic guitar, the body starts at the 14th fret.
Another design innovator was Orville Gibson, who manufactured guitars with arched tops (archtop guitars) in the 19th century.
In 1902, he founded the Gibson Company in Kalamazoo, Michigan. For decades, the Gibson company was a leading manufacturer of archtop guitars. The archtop prototype later evolved into the jazz guitar (e.g., L5 and Super 400).