There’s been a pretty major shake-up in the world of transit decarbonization. This summer, the California Air Resources Board – a state organization that regulates air quality – approved a rule mandating that by 2035, all new cars sold in California will be zero-emissions.    This rule will transform California's car market; and deliver some huge climate and health wins along the way. Between now and 2035, the regulation will result in 9.5 million fewer gas-powered cars on the road. California’s not alone in cracking down on gas cars – soon, as many as seventeen other states may follow suit, resulting in a wave of regulation that could change American transit forever.    This week, we’re talking with one of the state’s most influential environmental regulators, Mary Nichols, about how this ban on gas cars came to be, and how it will help the state make the big switch to a net-zero transit future.  The Big Switch is produced by Columbia University's Center on Global Energy Policy in partnership with Post Script Media. This episode was produced by Daniel Woldorff and Alexandria Herr Theme music and mixing by Sean Marquand. Story editing by Anne Bailey. A special thanks to Jen Wu, Natalie Volk and Kyu Lee. Our managing producer is Cecily Meza-Martinez. Our executive editor is Stephen Lacey.