Caltrain and the San Bernardino County Transportation Authority in California have taken significant steps to shift from diesel-powered trains to zero-emission electric, battery, or hydrogen fuel cell technologies. Caltrain, serving the San Francisco Peninsula, successfully launched zero-emission electric trains on August 11, with fully electrified service between San Francisco and San Jose commencing on September 21. This initiative, which began in 2016, involved installing overhead catenary wires along 51 miles of the route and procuring 23 seven-car train sets from Stadler. The transition is expected to reduce carbon dioxide emissions by 250,000 metric tons annually, enhancing air quality and reliability for Bay Area commuters. Similarly, the San Bernardino County Transportation Authority is preparing to introduce hydrogen-battery hybrid trains on a nine-mile route between San Bernardino and Redlands, with the first train arriving in June 2024. The agency's president praised the zero-emission technology, emphasizing its transformative potential. Meanwhile, other U.S. transit agencies like Metra and Massachusetts Bay Transportation Authority are also embracing battery-electric trains to reduce emissions and promote sustainability in public transportation. The wider adoption of zero-emission trains signifies a positive trend towards greener and more sustainable rail transportation across the country.