This report examines the potential use by cities in the United States of mechanisms for pricing carbon emissions. Carbon pricing has occurred almost exclusively at “higher” levels of government: national, multi-national, state/provincial, or multi-state/provincial scales. Nonetheless, as more U.S. cities adopt ambitious long-term goals and strategies for deep reductions in carbon emissions, there is growing interest in understanding the feasibility and potential impact of city-based pricing and in how the design and implementation of pricing mechanisms at scales that encompass cities might impact cities’ carbon-reduction efforts. The project’s research, interviews, and survey of 26 cities in the U.S. identified a set of Background Items, Findings, and Implications. Funding for this project was provided by the Summit Foundation.