This graph charts the decline and rise of inner-city populations in the four main cities since 1911. After a dip during the First World War, when people served overseas, the population recovered in 1921. It then began a long-term decline as suburban living became more affordable. A housing shortage during the Second World War saw a slight increase of residents living in Auckland and Christchurch, after which the downward trend continued until 1986. The rise in apartment living from 1991 saw inner-city populations increase in Dunedin and Christchurch, surge in Wellington, and skyrocket in Auckland.