Main North Road is the major north–south arterial route through the suburbs north of the Adelaide City Centre in the city of Adelaide, South Australia, and linking to Gawler on Adelaide's outer north-eastern fringes. Bus routes via Main North Road generally begin with the prefix "22x". The bus service is provided by Torrens Transit for Adelaide Metro.
History
Main North Road previously continued north past Gawler through Tarlee, Clare, Gladstone and Wilmington, South Australia, then via Horrocks Pass to end at Winninowie, following the route established in the early years of the colony by explorer John Horrocks as a major route for farmers and graziers to reach the capital, passing through rich farmland and the Clare Valley wine region. In 2011, the section of road between Wilmington and Gawler in SA's mid-north was renamed Horrocks Highway – to honour John Horrocks, an early explorer and pioneer in the region – and the section between Wilmington and Winninowie re-declared as Horrocks Pass Road, with the existing declaration of Main North Road truncated to officially begin at Gawler instead.
Main North Road was allocated National Routes 1 (between Gepps Cross and North Adelaide) and 20 (between Gawler and Gepps Cross) in 1955. The Whitlam government introduced the federal National Roads Act 1974, where roads declared as a National Highway were still the responsibility of the states for road construction and maintenance, but were fully compensated by the Federal government for money spent on approved projects.