The opening of the Auckland Harbour Bridge and the Auckland Northern Motorway between Northcote Road and Fanshawe Street in May 1959 saw State Highway 1 diverted from its former route around the Waitematā Harbour. Northern extensions of the motorway in 1969 (to Tristram Avenue), 1979 (to Sunset Road) and 1984 (to Dairy Flat Highway via Greville Road) diverted State Highway 1 off Wairau Road and Albany Highway. A motorway extension from Greville Road to Silverdale in 1999 bypassed Dairy Flat Highway, which was re-designated State Highway 17. In 2009, the Northern Motorway was extended to Puhoi, bypassing Hibiscus Coast Highway through Orewa which was re-designated part of SH 17. However, SH 17 was short lived, being revoked in September 2012 and reverting to a local arterial road.