A strong earthquake was recorded by Hudson's Bay Company trader–explorer Robert Campbell on December 27, 1850 at Fort Selkirk, Yukon Territory. A search of records from the region failed to find any other record of the earthquake. The duration of shaking and lack of aftershocks at Fort Selkirk suggest that the earthquake exceeded magnitude 6 and did not have a local source. The modified Mercalli intensity of VI or greater at Fort Selkirk is not compatible with lower intensities experienced there from large earthquakes along the plate margin and in the Mackenzie Mountains. The Denali fault system in southwestern Yukon and the southern Richardson Mountains are the most likely sources of the earthquake.