"Well, our allies are probably already at risk anyway, so it won't be bad to bring them to Dry City." Minos said right after hearing the comments of those three.
"But how will we do that?" Abby questioned him. "Currently, Dry City already has almost 500,000 inhabitants, and we have reached the maximum internal capacity of the area protected by the dome..."
After the events in Maritime City, the migrations to the Black Plain had continued until the Night News had released that edition in which it talked about Otis' execution.
That was because Minos' allied families in the region had continued to make their efforts to attract people to Minos' city until the date of that publication.
Only after that, the Nash, Cohen, and Stokes families, stop their actions since no one mentally sane would come to the Black Plain in the middle of a war of independence.