As a result, freshly imported young, strong, and healthy Africans were now much more affordable, cheaper in price, and more readily available in large numbers to the North American slave buyers, who by now had preferred to purchase them—even if they were distraught for a while and needed time to adjust to a new life enslaved at a plantation. From about 1700 to 1859, the majority of enslaved people who were imported to the North American mainland came directly from Africa in huge cargoes that were much-needed in order to fill the massive spike in demand for the heavy labour required to work the continually expanding plantations in the Southern colonies (that later became part of the present-day United States), with most enslaved people heading to Virginia, South Carolina, Georgia, Florida, and French or Spanish Louisiana.[15] Unlike the colonies in the South, the Northern colonies developed into much more urbanized and industrialized societies, and they relied less on agriculture as the main source of survival and growth for the economy, so therefore, they did not import many enslaved Africans, and the Black population which lived there remained fairly low for a very long time. However, big Northern cities like New York, Philadelphia, and Boston, had relatively large Black populations (both enslaved and free) for most of the colonial period and thereafter.