Do megaregions produce greater regional convergence or divergence? Implications for spatial planning and infrastructure investment

The population and economic activities encompassed by megaregions are ever expanding. As this occurs, investments are often recommended to ensure the regions are globally competitive from an economic standpoint. However, although such investment may accelerate growth in megaregions, that growth may have an uneven impact on the national economy. To date there has been very little empirical research on the relationship between the internal growth characteristics of megaregions and their effects on surrounding areas and the national economy. This paper examines the growth of megaregions within the context of regional convergence and divergence theory. U.S. counties are reorganized by megaregion to compare the inequality of counties and the extent to convergence in each megaregion. In particular, it uses the Theil index and conditional β convergence for measuring the relationship between growth, inequality, mobility, and social welfare. The results show a process of conditional β convergence at the national level but divergence among some megaregions. The core areas of megaregions, their socioeconomic characteristics, and their transportation infrastructure are identified as major forces of regional growth.