Histogram summarizing the completeness of the sample respect to the ALS III catalog for stars above the top reddening line of Fig. 11 (see Sect. 4.2.3 for more details), in bins of 250 pc of distance. Observed O9 – B9 stars are in green, while missing stars from the ALS III are colored in two gray colors: in dark gray, missing stars with B_mag < 9, and in light gray, stars with 9 < B_mag < 11. For each group, hatched areas indicate those stars with G_BP − G_RP > 0.5.