This paper tests whether the observed dominance of most city-pair markets and airports in the U.S. domestic airline industry by single carriers confers any pricing power on the dominant firms. The results of fixed-effects estimation indicate that airport dominance by a carrier does confer upon it substantial pricing power, whereas dominance at the route level seems to confer no such pricing power. Additionally, we find a positive, yet small, correlation between both route concentration, and price and airport concentration and price. The quantitative importance of airport dominance reveals that the most promising direction for public policy aimed at improving the industry's performance is to ensure equal access to sunk airport facilities.