In 1824, he explored the Finlay River and its tributaries in present-day north-central British Columbia, Canada, including the Muskwa, Omineca and Stikine for the HBC.
Assigned to work in the Athabasca Department (mostly in present-day Alberta) in 1805, Black served as a clerk there for fifteen years.
It is thought that Finlay may have decided to probe the northern branch of the Peace in order to determine if it afforded a better route to the Pacific than the one taken by Mackenzie.
Proceeding sometimes on foot, sometimes by raft, Black and a smaller crew explored the region of the Spatsizi Plateau, there finding one of the sources of the Stikine River and so reaching the boundary between the Arctic and Pacific drainages.
This posting allowed Black to exercise his renowned vigour in opposing competition, in this instance from American traders.
His difficulties in maintaining a good relationship with the local Nez Perce clients led to Black's transfer to the company's Thompson's River Post (now Kamloops) in 1830.
Here Black was murdered on February 8, 1841, shot by a nephew of Chief Tranquille of the local group of Secwepemc (Shuswap) following a minor quarrel.