A New Way of Measuring Urban Expansion and Contraction in New Zealand Towns and Cities, 1993-2021

Concerns about uneven regional development have focused attention on the long-run prospects of smaller towns in New Zealand. This paper examines changes in the physical extent of 133 New Zealand towns and cities between 1993 and 2021 using a reconstructed night-time lights dataset, exploiting the fact that urban areas emit light that can be observed from space. The reconstructed series combines the long temporal coverage of early satellite imagery with the spatial precision of modern sensors. A city-growing algorithm allows urban footprints to evolve rather than remaining constrained by administrative definitions. The results reveal substantial heterogeneity in urban trajectories. Rapid expansion is concentrated in commuter towns surrounding major cities and amenity-oriented settlements, while some smaller towns experience contraction associated with economic restructuring and changing locational advantages. Regional divergence in New Zealand therefore appears increasingly characterised by differentiated urban trajectories rather than by uniform decline among smaller settlements.