Critical period
Migration was the main factor that fuelled New Zealand’s population growth from the 1850s to the 1870s. 29% of the total net migration gains (people coming in minus people leaving) between 1840 and 2000 happened between 1861 and 1880. The two most important causal factors were the gold rush of the 1860s and the government-assisted immigration scheme of the 1870s.
Pākehā had replaced Māori as the largest ethnic group by 1860. This change was rapidly reinforced by high migration inflows as well as high rates of natural increase. Early migrants tended to be men of working age, which initially created a sex imbalance.
Later migration
After the 1870s migration was overtaken by natural increase (births minus deaths) as the main factor in population growth. However, it remained a relevant factor and has spiked up and down. Further significant net migration gains occurred in 1900–15, the 1920s, 1950–65, 1970–75, 1990–95, 2000–5 and 2013–18 (the latter at historically high levels). Notable net migration losses occurred in the late 1880s, the early 1930s, 1975–80, 1985–90, 1995–2000 and 2011–12. These were mainly associated with economic depressions or downturns. Some losses were caused by people leaving in significant numbers (the 1880s) while others were the result of relatively few people immigrating to New Zealand (1930s). The recent record gains reflect both fewer people leaving and more people arriving, among them an increase in New Zealanders returning from overseas, and historically high levels of people on student and work visas.
Asian immigration
The first Chinese immigrants came to New Zealand during the 1860s gold rush. The first group (12 men) arrived in Otago in 1866, and by 1869 over 2,000 Chinese men had settled there. Very few Chinese women came to New Zealand in that period – in 1881 there were nine Chinese women and 4,995 Chinese men. The wives of those men who were married remained in China.
New migrant groups
Migration was a much less significant cause of population growth in the late 20th century than the 19th – contrasting with the popular perception that New Zealand was becoming a society of migrants. However, there were many more Asian and Pacific immigrants than in the past. Both migrant groups have mainly settled in the Auckland region, which makes them more visible than if the populations were more dispersed. Increases in the Pacific population have been caused by migration reinforced by high rates of natural increase. Migration mainly accounts for the increasing Asian population – Asian fertility rates are low. Historically high levels of migration between 2013 and 2018 have resulted in migration again being the primary cause of New Zealand's growth. Arrivals from Asia dominate inward flows (45% for the 2017–18 period).
