Signed by the governors of California, Connecticut, Maryland, Massachusetts, New York, Oregon, Rhode Island and Vermont, the co-operative agreement has entered a six-month planning phase on how the states can work together to jointly build a market for electrically-powered vehicles – including cars, trucks and buses.

The initiative will include harmonized building codes and signage for charging points, establishing incentives and home charging packages for owners and the adoption of electric and hydrogen-powered vehicles on their own public fleets. By helping demand to rise, it is hoped that it will lead to lower up-front costs for new technology and a wider range of vehicles being offered by manufacturers.

Collectively, the eight states account for almost a quarter of all car sales in the United States, and are among a group which has signed an agreement requiring 15% of all vehicles sold to be electrically driven by 2025. Sales to date are rising quickly, from 17,000 in 2011 to 52,000 in 2012, and 40,000 in the first half of 2013.