As with buying a home and eating sushi, the wisdom of the decision to drive an electric vehicle hinges less on when you do it, and more on where. Today, you’ll find most EV owners in the few spots where there are ample places to plug in: mainly in California, in a few coastal states, and in major metropolitan areas.

That works OK for now; Americans have bought only about a million EVs to date. But many more are coming. The global auto industry is poised to roll more than 100 electrified car, truck, and crossover models onto showroom floors by 2022. Collectively, they’ll sell in the millions. That means the where question—where the electric vehicle owners will live, where they’ll drive, and most of all, where they’ll charge—is about to become much more important.

We may already, though, have the answer. A new analysis from the scientific research nonprofit International Council on Clean Transportation attempts to map out the charging infrastructure the US will need by 2025, by which point it predicts more than 3 million EVs will roam the country.

The researchers project that New York might need to add 35 percent more chargers every year; Boston, 27 percent; Portland, Oregon,, 23 percent; and Washington, DC, 20 percent. International Council on Clean Transportation

For the public and private entities building out that infrastructure, knowing where to put charging stations is essential. According to the analysis, most locales will need to up the number of plug-in places they build each year by 20 percent to keep up with demand. Even in California metros, where utilities and private companies already have plans to build more than 26,000 new stations by 2025, the analysis finds that the state may come up almost 41,500 chargers short.

“It's a tough position for cities—if they don't build enough charging stations the growth of EVs will be slower, hampering local climate and air quality goals,” says Costa Samaras, a civil and environmental engineering professor at Carnegie Mellon University who studies electric transportation and climate change. “But if they overbuild charging stations, it's expensive and these chargers might sit empty for a little while during the transition.”

Many cities, states, private businesses, and workplaces do have plans to build more charging stations. Electrify America, the initiative formed out of the EPA’s settlement with Volkswagen over its Dieselgate emissions scandal, is already starting to put in the first pieces of what will be a $2 billion charging network in 2027. (Some $800 million of those funds are already earmarked for California.) But that will not be enough, the researchers found.