“Nothing is as exciting. To read about cities and huge industrial enterprises, and really successful colonization. You can imagine what it might have been like. What Mars ought to be like,” (Dick 151).
Pris is here telling Isadore of the money to be made “smuggling pre-colonial fictions to Mars.” From this we gather that the colonization being referenced to is not that of Manifest Destiny, but of Mars before the start of the novel. Expansion always requires an influx of labor and money, either by getting both from the new colony or somewhere else, or by using labor to get the necessary money. The question of “what is human” that underlies every single thing in Do Androids Dream of Electric Sheep can be connected to the very same question of slaves of any nature at the beginning of their enslavement. In the United States, slaves were very clearly property, only even considered human for tax reasons, at the beginning. They were not considered to have souls, or a purpose (not exactly like the so-called lack of empathy andies and replicants show, though not unlike it) but at the same time could escape, and could live their own lives, and be intimate with others, albeit in fear of capture as is the same with the Nexus-6 replicants.
The replicants are controlled, are created by the society that controls them, are stigmatized, live on the borders of society at a lower caste, and can be retired legally and violently. Every single one of these facts coincides with the standings of slaves and former slaves in societies around the world.