It is commonly known that energy efficiency implementation has not achieved its technical or economically feasible potential in the United States, and many have attempted to quantify how much electricity the U.S. can save in the future. However, few have compared states to each other to determine why some states have been much more effective at using efficiency as a resource. This paper explores one aspect of the energy efficiency solution: how effectively has the United States used its electricity? RMI conducted this analysis on state-level electric productivity (measured in dollars of gross domestic product divided by kilowatt-hours consumed, or $GDP/kWh) to determine which states are the most productive with their electricity.