Note: this map has been updated: click here to view the update.

With technical and policy advice from WRI, three mandatory regional carbon trading markets are being established to limit states' greenhouse gas emissions, spur energy innovation and create green jobs. Twenty-three U.S. states are taking part, covering over half the U.S. population. Seven more states are formal observers. In September 2008, the Northeast and Mid-Atlantic Regional Greenhouse Gas Initiative (RGGI) began formal carbon trading. The Western Climate Initiative and the Midwestern Greenhouse Gas Reduction Accord are in development and will be operational by 2012.