The long changeover
Transportation produces more greenhouse gas than any other sector of the American economy, and most of that comes from ordinary light vehicles rather than from freight or aviation. That makes the car fleet the obvious place to look for reductions. It is also the place where the arithmetic is least forgiving.
There are more than 280 million light vehicles registered in the United States, and the average one on the road is over twelve years old. Both numbers have been climbing for decades, because cars are built better than they used to be and people hold them longer. Around 15 million new vehicles get sold in a normal year, which is a little more than five percent of the fleet. Even in a world where every new vehicle sold tomorrow ran on electricity, gasoline cars would still be a large share of what is on the road in the mid-2040s, because a car bought this year is somebody's used car in 2033 and somebody else's in 2039.
Electric vehicles have been running near a tenth of new sales in recent years, with wide variation by state. Norway got past ninety percent of new sales with a package of taxes, exemptions and parking rules held steady for two decades, which is the useful lesson in it: the policy has to outlast several election cycles to matter, because the fleet responds on a fifteen-year lag.
The practical obstacle in the United States is less about the cars than about where people park. A homeowner with a garage installs a charger and stops thinking about it. A third of American households rent, and apartment parking rarely has circuits available, which puts those drivers on public charging at higher prices and with the reliability problems that public networks are still working through. Until that gap closes, adoption keeps sorting by housing type.
Grid impact is smaller than the arguments suggest, provided the charging happens overnight, which most home charging does. The load is large in total and gentle in shape, and utilities have been planning around it for years. Fast charging along highway corridors is the harder engineering problem, since a single site can draw as much power as a small factory in short bursts.
Heavy trucks are a separate question with a separate answer. Battery weight comes directly out of payload, long-haul duty cycles leave little dwell time for charging, and the sector is testing several approaches at once without a clear winner. Short-haul and drayage duty cycles electrify well today, and a thousand-mile run still does not.