State Highway 20 (New Zealand)

State Highway 20 shield}}
State Highway 20
Southwestern Motorway
Map
Southwestern Motorway from Mount Roskill.jpg
The Southwestern Motorway seen from Puketāpapa / Mount Roskill in 2011
Route information
Maintained by NZ Transport Agency
Length25 km (16 mi)
Existed1977–present
Major junctions
South end SH 1 (Auckland Southern Motorway) at Manukau City Centre
Major intersections SH 20B (Puhinui Road) at Puhinui
SH 20A (George Bolt Memorial Drive) at Māngere
North end SH 16 (Northwestern Motorway) at Waterview
Location
CountryNew Zealand
Highway system
← SH 18→ SH 21
State Highway 20A marker
George Bolt Memorial Drive
LocationSH 20 at Māngere – SH 20A Airport
Length4.1 km (2.5 mi)
State Highway 20B marker
Puhinui Road
LocationSH 20 at Puhinui – SH 20B at Airport
Length2.3 km (1.4 mi)
Aerial view of the interchange between SH 20 (diagonal from bottom left to upper right) and SH 20A towards the airport (towards bottom right).
State Highway 20 as seen from Māngere Bridge, looking north

State Highway 20 (SH 20), also known as the Southwestern Motorway, is a New Zealand state highway linking State Highway 1 at Manukau with State Highway 16 in Point Chevalier, via Māngere and Onehunga. Along with its spurs, State Highway 20A and 20B, the state highway serves Auckland Airport, the country's largest, therefore making SH 20 a key arterial route connecting the airport to the wider Auckland region and most of the upper North Island. The route also forms the southern part of the Western Ring Route, a 48 kilometres (30 mi) motorway route bypassing central Auckland.