Christchurch can no longer officially be called New Zealand's second biggest city.
Latest figures show more than 10,000 people left the city in the year to June.
Although 1,700 arrived, the net loss of population is still almost 9,000 and represents a 2.4 percent reduction.
Statistician Kim Dunstan says that means urban Wellington now has a bigger population than urban Christchurch.
However he says the Christchurch City Council is still the second biggest in the country as Wellington is governed by a number of local authorities.