State gasoline and diesel fuel taxes are the most important sources of state transportation funding for highway maintenance and repairs. Thirty-six states levy a fixed-rate tax that has been in place for extended periods of time while others impose a variable tax rate. The primary objective of this study is to develop a multivariable econometric model to explain factors associated with variations in state gasoline taxes across 48 states. Three years of panel data, 2008, 2009, and 2010, were used to estimate the model, which controls for economic, climatic, and demographic factors at the state level. Three of the hypothesized variables were statistically significant. All of the hypothesized variables had the expected sign, with the exception of Income Per Capita. Results indicate that as the average temperature in the state declined one degree, the gasoline tax increased by $0.00451 per gallon. As per capita income increased, the gasoline tax decreased by $0.00000310 per gallon. As energy-related carbon dioxide emissions increased, the gas tax increased by $0.000000162 per gallon. The results of this analysis will have significant policy implications for revenue generation, highway maintenance, and transportation infrastructure.