Numerous studies have addressed the question of the econometric specification of the Environmental Kuznets Curve (EKC). This paper adds preliminary results on nonstationarity and its effect on functional form using a panel data set for the U.S. by state from 1929 to 1994. It is found that...

This is a survey paper of the recent literature on the application of semiparametric–econometric advances to testing for functional form of the environmental Kuznets curve (EKC). The EKC postulates that there is an inverted U-shaped relationship between economic growth (typically measured by...