The U.S. Acid Rain Program implemented a nationwide market for electric utilities' sulfur dioxide (SO2) emissions and included voluntary compliance possibilities for nonaffected sources. I observe significant voluntary participation 'albeit with small impact on the SO2 market' mostly from...

In September 2021, the city of Bogota' introduced a major market-based reform to its odd-even driving restriction, known as Pico y Placa. Since then, drivers have had the option to pay a daily congestion fee to be exempt from the restriction. We find t hat while the reform increased traffic, it...