The paper conducts simultaneous inference for conditional quantiles of the U.S. environmental Kuznets curve (EKC). To overcome slow convergence related to the asymptotic Gumbel distribution, the paper proposes simulation-based construction of the uniform condence band for the quantiles. Empirical results show that the EKC is an inverted-U at all quantiles and that the turning points for the higher quantiles come later than those for the lower ones. This leads to the asymmetry in the higher quantiles and thus the rejection of a quadratic function for them.