Highway 20 was first designated in 1930, serving as a bypass to the congested Highway 8. Soon after, a new cut was made into the Niagara Escarpment south of Stoney Creek, which would serve Highway 20 for 66 years. However, the new route failed to divert a significant amount of traffic from Highway 8. Subsequently, the Queen Elizabeth Way (QEW) was constructed through the Niagara Peninsula between 1937 and 1940. The opening of the Burlington Bay Skyway in 1958 bypassed the routing of Highway 20; it was truncated at the QEW in Stoney Creek in 1964 as a result. The routing remained unchanged between then and 1998, when all but a short stub of the highway was transferred to regional jurisdiction.