The quasi-biennial oscillation (QBO) is important for understanding the dynamical and chemical variability of the global stratosphere. Currently available wind data from the equatorial stratosphere extend back to 1953. Here we present reconstructions of the QBO extending back to 1900 that can be used to constrain climate model simulations. The reconstructions are based on historical pilot balloon data as well as hourly sea-level pressure (SLP) data from Jakarta, Indonesia. The latter were used to extract the signal of the solar semi-diurnal tide in the middle atmosphere, which is modulated by the QBO. The reconstructions are in good agreement with the QBO signal extracted from historical total ozone data extending back to 1924. Further analyses suggest that the maximum phases of the QBO are captured relatively well after about 1910.