SH 1 continues around the north-western city fringe of Christchurch, passing just east of Christchurch International Airport. In Christchurch, SH 1S originally ran via the town centre quite than around the outskirts by way of Harewood. Immediately after getting into the city of Wellington within the suburb of Linden, the Transmission Gully Motorway ends, and SH 1 merges on to the Johnsonville-Porirua Motorway. These roads traverse the central city 2-3 blocks southeast of the guts of the CBD. All these routes are unsigned and appear as native arterial roads on maps. Most previous sections of SH 1N reverted to native arterial roads, while the former part through Hamilton became the SH 1C spur. Nonetheless, SH 17 was short lived, being revoked in September 2012 and reverting to a local arterial road. The street between Rangipo (10 km (6.2 mi) south of Tūrangi) and Waiouru is commonly identified because the Desert Street. South of Timaru, the street again passes by gentle hill nation, staying near the coast however largely out of sight of it.

South of Waikouaiti the highway once more becomes steep, rising sharply over the Kilmog hill before dropping right down to the coast at Blueskin Bay, then rising again by way of Dunedin-Waitati Freeway (a two- to four-lane carriageway which was once designated a motorway) to the northern outskirts of Dunedin. It passes through Oamaru, from the place it turns inland briefly, crossing undulating hill nation before once more reaching the coast at Moeraki. It passes by Foxton, before reaching the tip of the plain at Levin. SH 1 follows the jap shore of the lake for 50 km (31 mi) to Tūrangi, at the southern finish of the lake. At Orewa, the motorway turns into toll-free, crossing farmland to the North Shore of Auckland. Here, the motorway ends, and SH 1 as a six-lane arterial road steeply descends by the Ngauranga Gorge to the Ngauranga Interchange, on the shore of Wellington Harbour. SH 1 enters the Manawatū-Whanganui Region, and descends via an army coaching space to the tip of the Desert Highway at Waiouru. At the southern end of central Dunedin, the freeway turns into the Caversham By-cross, which rises along the Caversham Valley before again turning into a motorway on the saddle of Lookout Level. For a lot of its route by way of Central Dunedin the highway is break up into two separate northbound and southbound roads, part of the city’s one-manner avenue system.

The Frankton route then turned the SH 1C spur in July 2022, with SH 1N being diverted to the newly-opened Hamilton section of the Waikato Expressway. The part of Marsden Level to Whangārei shall be upgraded to a four lane expressway as a part of the Roads of National Significance programme. Building of the 18.5 km (11.5 mi) Puhoi to Warkworth section began on eight December 2016 with the official sod-turning. In February 2018, NZTA began investigation into extending the Kāpiti Expressway additional northward roughly 23 km (14 mi) to only north of Levin, bypassing Levin and the villages of Ohau and Manakau. Turning southwards once more, SH 1 leaves Tūrangi and ascends onto the North Island Volcanic Plateau, passing by means of the fringes of the Tongariro Nationwide Park and into the Rangipo Desert, passing the volcanoes of Ruapehu, Ngauruhoe and Tongariro. At Bulls, SH 1 turns southeast to cross the river, turning southwest once more 5 km (3.1 mi) down the highway at Sanson. The opening of the Auckland Harbour Bridge and the Auckland Northern Motorway between Northcote Road and Fanshawe Road in Might 1959 saw State Freeway 1 diverted from its former route around the Waitematā Harbour.

For many of its size it is a two-lane single carriageway road with at-grade intersections and entry, sealed with chipseal in rural areas or asphalt in city and excessive-traffic areas. For nearly all of its size it is a two-lane single carriageway, with at-grade intersections and property accesses, in each rural and city areas. Since 2010 new roads have reduced the size from 2,033 km (1,263 mi). Land Data New Zealand. No. 2006-ln5284. New Zealand Gazette. No. 2024-au1843. New Zealand Gazette. Wikimedia Commons has media related to State Freeway 1 (New Zealand). For the history of realignments between Mackays Crossing and Linden, see State Highway fifty nine (New Zealand) and Transmission Gully Motorway. It gives a brand new alignment for State Highway 1 between Mackays Crossing and Linden, diverting the route from the Centennial Freeway between Paekākāriki and Pukerua Bay, in addition to offering an jap bypass of Porirua. SH 1K was assigned to the previous SH 1N route between Raumati and Peka Peka through Paraparaumu and Waikanae. Dunedin-Waitati Hwy looking north from near the Pigeon Flat Overbridge. Travelling north on SH 1 through the Rangipo Desert. The world between the Taieri and Waipori Rivers is flood-prone, and the freeway crosses this on a significant embankment known colloquially as the flood-free highway.