On 28 February 2023, how many states will be following the California emissions standard banning the sale of new emissions-producing vehicles by 2035?

In their ongoing effort to reduce the impacts of climate change, last month the California Air Resources Board (CARB) approved Advanced Clean Cars II which requires that all new passenger cars and trucks sold in the state to be electric, hybrid, or otherwise zero emission (New York Times, CARB). California is the only state that can implement emissions standards that are more stringent than federal requirements (CARB, Environmental Protection Agency). Other states can opt to follow federal guidelines or California guidelines, and a number of other states are moving to adopt these more stringent standards (Fox Business, The Hill). Such moves are contentious and California’s new standards are expected to be challenged in court (New York Times, The Hill).  

This question will be resolved by counting the total number of states that have the 2035 target that California has implemented in place on 28 February 2023. If any state’s emissions-producing vehicle ban is pending appeal on 28 February 2023, that state’s ban will still count toward the overall total.