The United States federal government, along with many state and local governments, have passed restrictions on electronic cigarette ("e-cigarette") sales with the stated purpose of preventing youth use of these products. The justification for these restrictions includes the argument that youth e-cigarette use will re-normalize youth smoking, leading to increased rates of cigarette smoking by teenagers. However, in this paper, we propose an evidence-based version of this model based on several years' worth of longitudinal and econometric research, which suggests that youth e-cigarette use has instead worked to replace a culture of youth smoking. [...]