The country’s roads are nearly twice as dangerous as the rich-world average. It doesn’t have to be that way.

The next time you are stuck in traffic, look around you. Not at the cars, but the passengers. If you are in America, the chances are that one in 75 of them will be killed by a car — most of those by someone else’s car. Wherever you may be, the folk cocooned in a giant SUV or pickup truck are likelier to survive a collision with another vehicle. But the weight of their machines has a cost, because it makes the roads more dangerous for everyone else. The Economist has found that, for every life the heaviest 1% of SUVs or trucks saves in America, more than a dozen lives are lost in smaller vehicles. This makes traffic jams an ethics class on wheels.

Each year, cars kill roughly 40,000 people in America — and not just because it is a big place where people love to drive. The country’s roads are nearly twice as dangerous per mile driven as those in the rest of the rich world. Deaths there involving cars have increased over the past decade, despite the introduction of technology meant to make driving safer.

Weight is to blame

Using data for 7.5m crashes in 14 American states in 2013-23, we found that for every 10,000 crashes, the heaviest vehicles kill 37 people in the other car, compared with 5.7 for cars of a median weight and just 2.6 for the lightest. The situation is getting worse. In 2023, 31% of new cars in America weighed over 5,000 lb (2.27 tonnes), compared with 22% in 2018. The number of pedestrians killed by cars has almost doubled since 2010. Although a typical car is 25% lighter in Europe and 40% lighter in Japan, electrification will add weight there too, exacerbating the gap between the heaviest vehicles and the lightest. The Ford F-150 Lightning weighs around 40% more than its petrol-engine cousin, because of the battery that moves all those lithium ions from cathode to anode.

This poses a giant collective-action problem. Individually, it is rational for people to buy bigger cars. As Tony Soprano once said to his son A.J. when discussing SUVs, “So you want to be the sucker in a regular car who gets decapitated?” Yet, the sum of those decisions is much more lethal roads, as well as more expensive car insurance.

In theory, regulators could insist that vehicles were lighter. Good luck with that. Pickup drivers love sitting behind the wheel of a huge truck. Running for election on a platform of banning massive cars would be a metrosexual caricature. In America, it is hard enough to persuade gun owners to embrace sensible gun laws, because of a mistaken belief that guns make people safer. For big cars, that argument is even harder to make, because up to a point it is actually true.

What then could make roads safer? As people become aware of the risk their choices impose on everyone else, attitudes to owning gigantic cars may change. This need not come at any cost to their drivers’ safety. We estimate that if the heaviest 10% of vehicles in America’s fleet shrank by roughly 1,000 lb, road fatalities in multi-car crashes would fall by 12%, or 2,300 a year, without sacrificing the safety of the heavier cars.

Attitudes can be nudged with reforms. Bizarrely, the government body that rates cars for safety did not propose taking the safety of pedestrians or other vehicles into consideration until last year. Because of a trade dispute with Europe over exports of poultry, many lighter foreign-made trucks are not even sold in America, a wrinkle known as the “chicken tax”. Tax deductions for working vehicles encourage people to buy trucks. Fuel standards, introduced in the 1970s to boost efficient vehicles, gave pickups a carve-out, inadvertently boosting their sales. The gradient could even tilt in the other direction. In 2022, France introduced a surcharge on new vehicles of €10 ($11) per kg over 1,800 kg (4,000 lb). In 2023, Norway began taxing car buyers at a rate of NKr 12.50 ($1.17) per kg over 500 kg.

Yet even if all those things were to change, consumer preferences are so strong that adjustments to fuel-efficiency standards would probably not be enough. That suggests another line of attack: as well as making cars lighter, you can make accidents rarer and less deadly.

In America, the first step should be to redesign the road system. In the early 1990’s, the French were about as likely as Americans to die in a car crash (which worked out as being about twice as likely to die per mile). Now they are three times less likely. Driving in Mississippi is four times as dangerous as in Massachusetts. In both cases, the design of roads explains much of the difference.

It may seem arcane, but the lack of roundabouts in suburban and rural America is a big cause of deaths. Replacing intersections would save thousands of lives a year. The spread of stroads, four-lane highways that sit next to shopping malls, mixing pedestrians and cars turning out into traffic with heavy vehicles travelling at 50 mph, is dangerous too. American highway engineers tend to associate wide lanes with safety. In fact, space encourages people to drive faster.

That points to a second step relevant everywhere: getting people to slow down. Because the energy — and hence destructive power — of a moving vehicle rises with the square of its velocity, finding ways to limit speed has an outsize effect. A good start would be to enforce the laws on speed limits that actually exist. Instead, plenty of American states ban speed cameras. More ambitious (meaning less popular) would be differential speed limits for heavier cars. Imagine the indignity of being overtaken by a Prius as you sit behind the wheel of your Chevy Silverado pickup, because you must travel 5mph more slowly to avoid being fined or losing your driving licence.

American car-nage

Ultimately, carmakers can innovate away a problem they have done so much to create. Better crash-avoidance technology and more pedestrian-protection systems with airbags would help. True self-driving cars, when they eventually become common, will greatly reduce the number of accidents and hence the death toll, even with heavy vehicles. Unfortunately, that could be years away. In the meantime, the task of saving lives will fall mainly to road engineers and traffic cops.