Does road accessibility to cities support rural population growth? Evidence for Portugal for the 1991-2011 period

Transport investment is frequently advocated as having the double virtue of achieving both economic growth and territorial cohesion. The idea is that improving the accessibility of lagging regions to cities, increases the attractiveness of those regions for people and businesses. However, transport is only one of the factors affecting local development and there is no consensus on its net effect on population growth. The large scale of public funding allocated to motorway investment since the country joined the European Union in 1986 makes Portugal an ideal case study to examine the potential effect of improved road accessibility on the development of lagging rural areas. In this paper, we investigate the relationship between rural population change and road accessibility to the urban hierarchy (i.e. cities of different sizes) between 1991 and 2011. Regression analyses show that rural population growth is negatively associated with road distance and road travel time to the urban hierarchy, notably to medium-sized cities (i.e. 20,000-99,999 inhabitants). This suggests that medium-size cities play an important role in supporting population growth in their rural hinterlands. Robustness tests confirmed the validity of these findings. There is no evidence of nonlinearities in the magnitude of the effect between accessible and remote rural areas, which may be partially related to the relatively small size of the country.