Production of the Martin 000-21 began in 1902 and ended in 1959. When first introduced the Martin 000-21 had a cedar neck with a 19 fret ebony fingerboard, joining the body at the 12th fret. In 1923 Martin changed the neck to mahogany and added an extra fret. From 1932 onwards pickguards were an option. In 1938 the fingerboards joined the body at the 14th fret (instead of the 12th fret as on earlier models). Finally from 1947 - 1959 rosewood was used (instead of ebony) for the fingerboards and bridges.