Answer:
Places like Boston focused on protecting runaway and freed slaves mainly because that region was the cradle of American liberalism, that is, the place where the American Revolution originated, the ideas of freedom and equality that later moved into the French Revolution, and a series of egalitarian social and cultural values regarding the human conditions of the different ethnic groups, which promoted the egalitarian valuation of Afro-Americans with respect to whites.
This, added to the lower presence of conservative religious values in the region, made the human condition of the slaves to be valued above the commercial interests that arose from their exploitation.
