On the African coast, pronounced shifts in both regions of provenance and the strategies of slave traders occurred during the illegal era. The slave trade had not evolved in all areas of Africa at the same time, nor, indeed, did it decline uniformly in response to attempts to suppress it. The sheer human and environmental diversity of sub-Saharan African societies made such an outcome unlikely. Rather, a series of marked or stepped declines in individual regions contributed to a more gradual trend for sub-Saharan Africa as a whole. Although the overall dominance of West-Central Africa in the transatlantic slave trade is well recognized, it is not generally appreciated how important the region was in its last half century. In this period, that area dispatched more people than all other regions combined.
Reviewing the patterns of the traffic from north to south, we can see that in Upper Guinea (Senegambia, Sierra Leone, and the Windward Coast) slave trading gradually declined after 1820 before ending rather suddenly in the early 1840s, though it ended first on the Windward Coast.
On the Gold Coast, departures after 1820 were occasional and never more than a few hundred a year, but a further forty years passed before the traffic ended completely. In the Bight of Benin, traffic peaked in the first half of the eighteenth century. It was nevertheless the part of West Africa where the slave trade persisted longest. Almost all the captives leaving the region after 1830 passed through Lagos and Whydah, with the latter port remaining active into the mid-1860s. In the adjacent Bight of Biafra region, by contrast, the traffic ended in the early 1840s, while the relative role of southeast Africa, heavily involved in the Indian Ocean slave trade, increased in the closing half century of the transatlantic traffic. Overall, in the nineteenth century, the center of the slave trade from sub-Saharan Africa shifted strongly southward.