This corpus study constitutes the first quantitative style analysis of Choro, a primarily instrumental music genre that emerged in Brazil at the end of the 19th century. We evaluate its description in a recent comprehensive textbook by transcribing the chord symbols and formal structure of the 295 representative pieces in the Choro Songbook. Our approach uncovers central stylistic traits of this musical idiom on empirical grounds. It thus advances data-driven musical style analysis by studying both harmony and form in a musical genre that lies outside the traditional canon.