The Average and Heterogeneous Effects of Transportation Investments: Evidence from Sub-Saharan Africa 1960–2010
利用39个非洲国家50年的道路和城市数据，估计市场准入对城市人口的影响，发现弹性约为0.08-0.13，且对小城市和偏远城市更强。
Abstract Previous work on transportation investments has focused on average impacts in high- and middle-income countries. We estimate average and heterogeneous effects in a poor continent, Africa, using roads and cities data spanning 50 years in 39 countries. Using changes in market access due to distant road construction as a source of exogenous variation, we estimate a 30-year elasticity of city population with respect to market access of about 0.08–0.13. Our results suggest that this elasticity is stronger for small and remote cities, and weaker in politically favored and agriculturally suitable areas. Access to foreign cities besides international ports matters little. Additional evidence points suggestively to rural-to-urban migration as the primary source of this population increase, though we cannot fully rule out natural increase or reallocation across cities.