A number of United States (U.S.) cities are proposing and implementing bold sustainable solutions in order to combat the social, environmental, and economic impacts of climate change. Cities of all sizes around the country are taking control by pledging to reach community-wide goals of 100% renewable energy. However, many of these cities are unsure of how to meet these commitments. Although the renewable energy potential throughout the U.S. is strong, cities are facing other types of challenges that are hindering their ability to progress swiftly to meet the commitment.