Distance of the groups shown in Figure 2 away from the center of the expansion of Barnard’s loop. To remove contamination from the groups unrelated to this expansion (e.g., L1641, λ Ori, Orion B, or those that predated the significant formation of stars in the Complex), the groups were limited to be within 40 pc of the center, with ages between 4 and 10 Myr. Dotted lines show the traceback over the time that predates the formation of the group, solid black lines shows the distance to the center from the time corresponding to the star-forming epoch to the present day. The red line shows the median distance of all groups at a given timestep.