Rhode Island has fallen. The trucks have taken over. The Ocean State was the last bastion of majority-car culture, the final holdout against a rising tide of trucks, a category that includes pickups, vans and SUVs.

The revolution happened fast. From the time the Federal Highway Administration’s registration data began in 1900 until the late 1980s, cars ruled the nation’s roadways. But in 1989, the trucks claimed their first state, Alaska. A trickle of trucky states in the Mountain West and Northern Plains followed, but most states didn’t turn truck until after the Great Recession, when crossover utilities conquered the suburbs.

The truck tidal wave appeared to crest in 2012, when more than a dozen states flipped, but that was probably a reflection of earlier trends: In 2011, the Federal Highway Administration updated its sources, definitions and methods to more accurately track trucks, which include pickups, SUVs, vans, crossovers and, in this case, commercial and government vehicles.

Even after that update, a few East Coast states held out. But New York became minority-car in 2014; Massachusetts, Maryland, Connecticut and New Jersey then toppled in rapid succession. The last domino fell in 2018, when even the roads on Rhode Island’s islands became stuffed with trucks. (Despite the seeming ubiquity of the Honda Odyssey minivan, Washington, D.C., is still majority car.)

Why did the truck takeover snowball? A simple and true explanation would be that America has unusually cheap gasoline and many people find bigger vehicles to be more convenient.

But an even more true explanation might be that colossal car conglomerates with colossal advertising and lobbying budgets have strong incentives to sell us light trucks, the definition of which can fluctuate.

As a rough rule of thumb, cars typically have two rows of seats and a trunk or hatchback, while light trucks are typically built on a truck chassis. Or, in the case of many crossovers, they’re built on a car chassis with special features added for off-roading.

Whether a vehicle is classified as a car or a truck is, therefore, subject to some interpretation. For now, the important point is that trucks generally are more profitable than cars thanks to two big government incentives, both of them historical footnotes.

The first is the so-called chicken tax, a 25 percent tariff imposed by Lyndon B. Johnson in 1964 on foreign-built work vehicles as part of a chicken-related trade war with Europe. If you’re making a pickup or cargo van in the United States, profits should be higher, because foreign factories can’t come close to undercutting you on price.

The second incentive lies in the fine print of Corporate Average Fuel Economy (CAFE) standards adopted in 1975, Gerald Ford’s reluctant response to a crippling Middle East oil embargo that sent gas prices soaring. To protect American commerce, work trucks and light trucks were subject to less-strict CAFE standards than family sedans. Trucks are also exempt from the 1978 gas guzzler tax, which adds $1,000 to $7,700 to the price of sedans that get 22.5 or fewer miles to the gallon.

Those incentives encouraged American car manufacturers to double down on trucks. But the CAFE standards also had a more subtle and far-reaching effect: They pushed carmakers to broaden the definition of truck.

“Cars and light trucks had two different standards. It became easier to meet the standard with trucks. So automobile manufacturers thought of ways to basically build trucks that are really cars, and that’s what generated the SUV,” said Massachusetts Institute of Technology economist Christopher Knittel, who has spent much of his career tracing the unintended consequences of government fuel regulations.

A half-century ago, if you needed to haul 3.5 kids, hamburger buns and a standard poodle, car companies would happily sell you a station wagon, and you’d be counted on Team Car.

Today, if you show up with the same cargo needs you’ll be steered toward a crossover SUV — an eerily similar vehicle serving an eerily similar purpose, but one that comes with a few extra bells and whistles that just so happen to allow manufacturers to classify it as a “light truck,” regardless of whether it’s actually well-suited to off-roading or hauling. Now you’re on Team Truck.

“They’re responding to the definition, for regulatory purposes, of what a light-duty truck is,” Knittel told us. “If they can, they’ll make a small tweak to a vehicle and get it to be classified as a light truck, even though the vehicle itself hasn’t changed at all.”

In fact, if you look at the list of SUVs on fueleconomy.gov, maintained by Oak Ridge National Laboratory, you will see something genuinely mind-bending: The Toyota Corolla Cross 4WD. By some incredible alchemy, and by at least one definition, a variant of the Toyota Corolla — the archetype of a frumpily efficient family sedan — has evolved into a light truck.

“Corolla represents the entry point to the Toyota lineup,” Toyota’s Ben Haushalter said via email. “As customer tastes change over the years, our strategy of offering varied body-styles within the Corolla brand has changed accordingly.”

Virtually all the growth in trucks has come not in pickups or vans, according to data from the Environmental Protection Agency, but in SUVs, a category now led by the mushy middle of crossovers-that-probably-should-have-been-station-wagons.

The truck transformation’s environmental toll comes with an asterisk. Thanks in part to rising CAFE standards and tightening truck definitions, data shows that fuel economy has actually improved. In 2021, the typical new SUV got about 24 miles per gallon — about the same as the average sedan in 2007. Our friend the Corolla Cross gets 30 miles per gallon, a benchmark its self-effacing sedan forebears couldn’t meet just a decade ago.

America’s fuel consumption peaked in 2004, during the 12-mpg-Ford Excursion era defined by ultralow gas prices and ultra-big SUVs. Fuel consumption has since fallen, according to the Federal Highway Administration, even as the light-truck share of the market has roughly doubled. But over the past decade, as SUV adoption has soared, that progress appears to have stalled.

Meanwhile, manufacturer profits aren’t the only thing pushing us toward SUVs. Drivers, too, face incentives — 4,500 pounds of them — every time they pull onto the highway. That’s how much the average new light truck weighed in 2021, which is about 1,000 pounds more than the average sedan or wagon.

The profusion of taller, heavier vehicles changes the road-safety equation, Knittel told us, making their drivers safer and people in smaller vehicles less safe. Design changes and technological advances have narrowed the gap, but large vehicles remain safer than their petite peers. That may help explain why SUV adoption has accelerated. It’s a feedback loop: As cars get larger, everyone feels pressed to buy a larger car.

And it’s not just other drivers who suffer in this mobile arms race. Pedestrians and cyclists are increasingly imperiled on roads dominated by trucks. Nearly 7,400 pedestrians were killed in 2021 according to the National Highway Traffic Safety Administration, the highest figure in four decades, and preliminary estimates from the Governors Highway Safety Association show 2022 could be even worse.

“We’ve made cars safer and safer for people in them, but as we have done that, we’ve made it increasingly less safe for people outside of them,” said Rebecca Sanders, founder of Safe Streets, a pedestrian- and bicyclist-safety specialty firm headquartered in Portland, Ore.

The peril posed by supersized pickups has been well chronicled. But while regulators are racing to promote technology-assisted safety measures, even a crossover can be more dangerous than a sedan, Sanders told us. It’s physics: The extra weight of a small SUV dumps more kinetic energy into a human body upon impact, and hits that body at a higher point, leading to more serious injuries.

“If you were to be hit by a sedan, you’d likely be hit in the leg, maybe pelvis for a school-aged child,” Sanders said. “But today’s gargantuan trucks will hit an adult in the chest or even the head. And even the crossover will be more likely to hit your pelvis or belly, where your vital organs are located.”