The E4ST Fast Predictor is based on a highly detailed simulation model of the electric power system and its environmental impacts that has been developed for the continental United States and the connected parts of Canada and Mexico. This model utilizes network reductions for the three interconnections that include all high voltage lines of 230kV and above. Since running the simulation model itself is time consuming and involves optimizing several million variables across the three interconnections, to demonstrate the capabilities of the model and to explore electric power futures for the United States under different assumptions and policies, the Fast Predictor has been developed. By fitting a very accurate statistical regression model to the output from a large number of E4ST simulations, the output variables can be predicted based on the user’s choice of input variables, and nearly instantaneous estimates can be obtained for all of the output variables listed in the preceding paragraph for 2012, 2025, and 2035. The input variables selected by the user include such things as high or low natural gas price projections, the solar capital cost trend, solar and wind subsidies, CO2 charges, etc.