a,b, The number of introductions of EVD into a health zone positively correlates with the number of exportations out of a health zone (r2 = 0.48, p < 0.001), with most movement events occurring into and out of the same 5 health zones (Mabalako, Kalunguta, Katwa, Beni, and Mandima). State reconstructions that are less than 80% certain are excluded. c, Heatmap showing the frequency of lineage migration between all pairs of affected health zones. A migration event is counted only if the phylogeographic reconstruction for both the source and the sink health zones is at least 80% certain. d, The duration of time that a lineage circulated within a health zone is weakly correlated with the number of introduction events that a lineage seeded into other health zones (r2 = 0.21, p < 0.003).