We analyzed the aggregation and diffusion of population distribution in Niigata, Toyama, Kanazawa, and Fukui, the prefectural capitals of the Hokuriku region, using regional grid data from the 2005, 2010, 2015, and 2020 national census. The analysis methods included aggregating time-series data on the population in and outside the urbanized area, determining the population and the number of grid parcels by population class, and estimating population density functions. The results showed that the ratio of the residential population within the urbanized area increased in each city, indicating that the urbanized area system is effectively functioning in terms of population acceptance. In Toyama City, the population tends to be concentrated in densely populated areas, indicating a movement toward the establishment of an intensive city. On the other hand, in Niigata City, Kanazawa City, and Fukui City, the proportion of population living in densely populated areas is decreasing, and especially in Fukui City, the population distribution tends to be spatially diffuse.

The authors analyzed concentration or diffusion of the population distribution in Toyama City, Kanazawa City, and Fukui City based on mesh-based national population census data of 2005, 2010, and 2015. We aggregated the population and number of plots for each mesh, and estimated the population density function. As a result, the population distribution in Toyama City and Kanazawa City tended to be concentrated, and that in Fukui City tended to be diffused. It was also shown that the population of the most densely populated areas in all three cities was declining, while the population was being concentrated in the moderately dense areas. Furthermore, it was shown that the population was being concentrated in the urbanized area. On the other hand, there were area where residents had settled newly in all three cities, and the urban space tended to expand.