In solid lines, we plot the fraction of cores which have a 24 μm counterpart (red solid line, triangles) and those without 24 μm counterparts (black solid line, diamonds). We plot this fraction only for targets which have available MIPS 24 μm data, as indicated in Table 4. The dashed line represents how the fraction of 24 μm bright/dark cores would change if the cores in the nearest bin were placed in the progressively larger distance bins. The uptick at large distances of 24 μm-bright fraction is due to the particularly active IRDCs at these distances.