Some U.S. drivers may soon see a new expense at the gas pump: the cost of taking the global-warming fight on the road. New York and four other states are exploring ways to put a price on the air pollution spewing from cars, trucks, trains and other vehicles — the source of more than a third of greenhouse-gas emissions in the northeastern U.S. The result may eventually be new taxes, tolls or a pollution-trading system that could raise $3 billion a year or more for mass transit, electric-vehicle rebates and other projects, supporters say. With the Paris climate deal in the rear-view mirror and governments moving already to put a price on industrial emissions, especially from power plants, regulators are starting to focus on tailpipe pollution. “Transportation is one of the largest sources of carbon dioxide emissions in the nation and innovative strategies are needed to reduce these emissions,” […]