Small amounts of LNG have been transported by rail on a trial basis in Alaska and Florida. But if the new rule is adopted, trains of 100 or more tank cars, each with a capacity of 30,000 gallons, could start carrying LNG, primarily from shale fields to saltwater ports, where it would be loaded onto ships for export. They could traverse dozens or hundreds of different jurisdictions across the country, some that rely on volunteer firefighters as first responders, while others are major population centers.