History of King's Highway 61B:
King's Highway 61B was a business route that was established in 1968 through Fort William, which later became part of the City of Thunder Bay. The Lakehead Expressway was completed around Fort William in 1968. The route of Highway 61 was relocated onto the newly-completed bypass. The bypassed section of Highway 61 through Fort William was redesignated as Highway 61B. Even at the time of the route's creation in 1968, nearly the entire route of Highway 61B was under municipal jurisdiction. Only a short section of Highway 61B from the new Lakehead Expressway to the City of Fort William limits near Mosquito Creek was under the jurisdiction of the Department of Highways of Ontario (DHO), However, the creation of the City of Thunder Bay in 1970 resulted in many changes in terms of the administration of roads in Fort William, Port Arthur and the surrounding townships. Upon amalgamation in 1970, the balance of Highway 61B that remained under DHO jurisdiction was transferred to the newly-created City of Thunder Bay, effective September 21, 1970. Since that time, Highway 61B has been a municipally-signed business route. It is interesting to note that Highway 61B was omitted from all Ministry of Transportation mileage tables after 1989, even though the route continued to be shown on the Official Road Map of Ontario up until 1997. Also, the route of Highway 61B was not marked on the Official Road Map between 1982 and 1986, most likely the result of a cartographic error. It is believed that the signing of Highway 61B was discontinued in 1997, at the same time as the two other Thunder Bay Business Routes of Highway 11B & Highway 17B.
The route of former Highway 61B was severed in 2013. A mysterious fire on the James Street Bridge on October 29, 2013 prompted CN Railway to close the James Street Bridge over the Kaministiquia River to highway traffic and pedestrians. The bridge remained closed for several years. This unique bridge had previously allowed highway traffic and railway traffic to use the bridge at the same time, since the traffic lanes were cantilevered out on deck extensions from both sides of the main railway bridge in the centre. After lengthy discussions between the City of Thunder Bay, CN Railway and the Fort William First Nation about the future of the James Street Bridge, the structure was reopened to traffic in the Fall of 2019.