With increasing concern about carbon dioxide emissions from power generation, high natural gas costs for generating electricity, and rapidly increasing costs of constructing new power plants, energy efficiency programs are being given greater consideration by utilities and regulators. This study reports on a statistical analysis of the relationship between state-level efficiency program effort and growth in electricity sales between 2001 and 2006 in the United States. The higher the utility efficiency program expenditures per capita and the greater the range of other efficiency programs offered, the greater the reduction in the growth of power sales. Application of the portfolio of energy efficiency programs used in the states with most aggressive programs would have reduced the growth in a state's electricity sales by about 60% relative to the case where no efficiency programs were implemented. (C) 2008 Elsevier Ltd. All rights reserved.