13 other states adopt the California way

Automakers acknowledge that they’re especially worried about a lengthy fight between California and the Trump administration that splits the car market. In a June letter to President Trump, 17 major car companies pointed to the risk of “an extended period of litigation and instability, which could prove as untenable as the current program.” (To be clear, they weren’t asking to stick to the Obama-era standards; in a separate letter, the car companies asked California Gov. Gavin Newsom to meet the Trump administration half-way.)

After all, California brings some serious backup to a battle over the country’s cars. Although other states are barred from making their own clean car rules, they can adopt California’s — and a lot of them have. The 14 states (including California) that already require car makers to comply with California’s standards for tailpipe and greenhouse gas pollution make up more than a third of the market for cars and light-duty trucks. And ten of them also follow California’s rules requiring carmakers to sell zero-emission vehicles such as electric cars in their states.