This paper reviews the environmental Kuznets curve (EKC) literature, which postulates an inverted-U association between pollutants and economic output, suggesting that economic growth initially leads to greater environmental deterioration at low levels of income, but that factors may eventually cause an improvement in environmental quality with further economic development. A systematic review was conducted using the bibliographic map method to identify the main research streams and to identify possible gaps and areas for future research. Six research streams were identified: testing the basic EKC equation, critique of EKC, determinants of EKC, review of EKC, a nexus of income-energy consumption and new environmental indicators.