Power plants have been the biggest source of greenhouse gas emissions in the United States for more than 40 years. But according to new data from the U.S. Energy Information Administration, transportation has now claimed the top spot.

The U.S. transportation sector — which includes cars, trucks, planes, trains, and boats — now emits 1.9 billion tons of CO2 annually. The electric power sector emits 1.8 billions tons.

The decline in power sector emissions since the mid-2000s isn’t due to Americans using less electricity, but rather that the energy is being produced by less carbon-intensive sources, such as the switch from coal to natural gas and the growth in wind and solar power, Bloomberg reported.

Energy experts say transportation emissions are also likely to decline in the coming years as fuel efficiency increases and as electric and hybrid vehicles become more common. The number of plug-in electric vehicles sold each year in the U.S. increased by a factor of eight between 2011 and 2016, according to Climate Central. The number of publicly available charging stations has also tripled since 2012.

For more details on the global surge in electric vehicles, click here.