The route north of Wellington known as the "Centennial Highway" from Ngauranga to Paekākāriki was started in 1936 and opened on 4 November 1939. The Centennial Highway project involved an upgrade of the Ngauranga Gorge road and provided a new route from Paremata to Paekākāriki, bypassing the winding road along the southern harbour edge from Paremata to Pāuatahanui and the tortuous narrow winding Paekakariki Hill Road between Pāuatahanui and Paekākāriki. It followed a new route, bridging the narrow channel between Paremata and the Mana isthmus and following the eastern edge of the Taupō swamp north of Plimmerton before climbing to the Pukerua Bay saddle and descending to follow the coastline to Paekākāriki.