King's Highway 74, commonly referred to as Highway 74, was a provincially maintained highway in the Canadian province of Ontario that travelled north from Highway 3 at New Sarum to Middlsex County Road 29 (Hamilton Road) on the outskirts of London. The 22.4-kilometre-long (13.9 mi) was assumed by the province in September 1937. Aside from paving and the construction of an interchange with Highway 401, it remained generally unchanged for the next six decades until it was decommissioned in 1997 and transferred to Elgin County and Middlesex County. The road has since been redesignated as Elgin County Road 74 and Middlsex County Road 74.