The Trump administration’s recent assault on California’s clean vehicle policies will not only hurt residents of the state, but in the long run will crush the competitiveness of American car companies. The myth that California’s stringent vehicle emissions requirements have hurt United States’ carmakers is simply not true. The state’s 1990 Zero-Emission Vehicle Mandate and other policies have created fertile ground for start-ups with bold ideas to try, succeed and excel in markets around the world. Tesla , a Silicon Valley company, is now the No 1 electric vehicle manufacturer in the world; its Model 3 outsold the small and mid-sized luxury cars, the Lexus ES, BMW 3 series and Mercedes C-Class combined, in the third quarter this year, despite the US federal rebate shrinking to a quarter of its original amount at US$1,875. More impressively, during the same quarter, Tesla’s Model 3 was also the sixth-bestselling car in the US, beating cheaper models such as Hyundai Elantra, Nissan Sentra, and Ford Fusion. Globally, the Model 3 has caught the imagination of European consumers, becoming a top seller of all vehicles in Norway, the Netherlands, and (briefly) Switzerland, the world’s three wealthiest nations. In Europe, the Model 3 also briefly outsold its three German competitors in the premium mid-sized sedan market. Having teamed up with Fiat Chrysler Automobiles, Tesla is expected to sell more next year, as manufacturers will start to pay fines if the average carbon dioxide emissions of their new cars sold in Europe exceed 95g/km . California has the largest zero-emission bus and truck fleets in the nation, mostly thanks to Proterra and BYD USA . It has the largest population of fuel cell electric vehicles in the world, with hydrogen refuelling stations stretching across the elongated state. Tesla, along with Waymo , Cruise , and other California-based companies, is also a leader in automated vehicle technologies, with over half a million autopilot-enabled global drivers providing on-road feedback. Uber and Lyft , the two ride-hailing giants that are potential providers of automated, shared-mobility services, are also based in California. These achievements did not happen in a vacuum. Who developed the world’s most stringent emissions standards, creating the first market for zero emission vehicles in the early 1990s? California. Who enforced its rules and uncovered Volkswagen’s “dieselgate” scandal , solidifying zero emission vehicles’ role in a carbon-neutral transport system? California. Who pioneered the Zero-Emission Vehicle Mandate that has greatly rewarded risk-taking zero emission vehicle start-ups with monetised credits? California. Who created the world’s first low carbon fuel standard that, with its credits, encourages the zero emission vehicle infrastructure build-up and the operation of zero emission vehicles? California. Who adopted the first comprehensive renewable energy policy in the US, leading the nation in terms of the proportion of clean electricity generated by utility-scale power plants (1MW or larger)? California. And, who created a broad ecosystem to encourage clean technology and business innovations that has sparked so many great companies? Yes, California. The California system is so successful that China has borrowed and improved on its Zero-Emission Vehicle Mandate and invited Tesla to open its Gigafactory in Shanghai. Soon, Tesla will compete against Chinese electric vehicle makers in the world’s largest car market, selling zero-emission vehicle credits to legacy car manufacturers. The open-door policy is a strategic shift, aiming to make China the hotbed of car technology innovations. So if US President Donald Trump is genuinely serious about making America great again, he should adopt California’s clean vehicle policies nationwide and create the world’s largest zero-emission vehicle market. In this way, Tesla’s Model 3 may outshine Ford’s Model T, allowing the US to lead deep into the 21st century. Yunshi Wang is director of the China Centre for Energy and Transportation at University of California, Davis and a co-director at the US-China-the-Netherlands Zero Emission Vehicle Policy Lab. He advises California government agencies on global zero-emission vehicle policies. The author and associated centres have no financial relationships with the electric vehicle companies mentioned in this article