The only train station in Houston, the US’s fourth-largest city and one of the fastest-growing conurbations in the country, is a diminished, morose sight. Intercity trains arrive at this squat, shed-like Amtrak building, which cringes in the shadows of roaring highways, just three times a week.

That such a meager train station could ostensibly serve a metropolitan area of about 7 million people is a stark symbol of how the sprawling, car-dominated US has fallen behind cities around the world where people can rely on extensive, high-quality public transport to get around.

The gap is now so large that for major American cities to bring their public transit up to “world-class” status, it would cost an enormous $4.6tn, involving 7,500 miles of new dedicated infrastructure for trains and buses, over the next 20 years, a recent report found.

American cities languish badly compared with global leaders such as Sydney, Hong Kong and Barcelona, based on the number of transit vehicles per 100,000 residents, according to the Transportation for America study.

How people get around matters in terms of convenience, but also human and planetary health. Globally, transportation accounts for about a third of all planet-heating emissions, with the sector’s emissions doubling since 1990 amid a growing thirst for oil to power more cars, planes and ships.

With global demand for passenger transport expected to nearly triple by 2050, an expansion of efficient, affordable public transport is critical in helping address the climate crisis and toxic air pollution. The need for better public transit has been underscored, too, by recent soaring gasoline costs that have hit car drivers around the world.

The research defines world-class transit as being an “accessible, frequent, reliable and convenient alternative to automotive travel” and bases its ranking on transit vehicles given the large variance in fares and funding among countries.

Houston has just 16 transit vehicles per 100,000 people via its bus and light rail system, the study says, compared with 118 in Paris – a city with a similar population that has embraced cycling and walkability. Detroit has eight, Indianapolis has seven and Oklahoma City has just six. Frisco and McKinney, a combined urban area of 500,000 people near Dallas, has none at all. By comparison, Vienna has 120 buses and trains per 100,000 residents, while Montreal has 107.

Only New York City, boasting the premier subway system in the US, approaches world-class standards, but still has fewer transit vehicles, proportionally, than Tehran. Ridership per capita in New York, the most walkable, transit-rich American city, lags below that of Bengaluru, Santiago and Warsaw, according to a separate 2023 study.

Across the world, too, there are large disparities. In terms of per capita use, places in east Asia such as Hong Kong and Taipei rank highly, while several big African cities such as Johannesburg and Lagos struggle. Within Europe, there is a gap, too – cities such as Moscow and Budapest perform well in data on the number of transit vehicles and annual users, Lisbon less so.

“When people travel abroad, they always talk about what a phenomenal experience the public transit is, it blows their minds,” said Kari Watkins, a transit expert at the University of California, Davis. “The difference to the US is so obvious. Yet we are still such a car-centric society – change hasn’t played out politically.”

Car dependence permeates rural regions in Europe, but most major cities are served by public transport networks that stretch deep into the suburbs. In recent years, densely populated capitals such as London and Paris have taken steps to catch up with frontrunners such as Copenhagen, Amsterdam and Vienna, where cars account for fewer than one in four journeys.

Unlike in much of Europe, people in the US often have little choice but to rely on cars. Those unable to drive due to age, disability or the rising costs of car ownership that have only worsened amid the Iran war routinely face a laborious gauntlet of patchy public transport options.

“Essentially, you are forced to live like a second-class citizen without a car,” said Watkins. “It will take you twice as long to get anywhere, and it probably won’t be a nice experience. You are almost always choosing that it will take longer than in a car.”

While the amount of money needed to remedy this situation appears astronomical, it pales compared with the $6.3tn the US will spend on highways in the same period over the next 20 years, Transportation for America points out. Transportation funding invariably means road funding in the US, with about 80% of all federal transport dollars going towards highways.

“In a lot of places, the public transit experience is mediocre, but the problem isn’t money – it’s that the priorities are wrong,” said Corrigan Salerno, policy manager at Transportation for America.

“Steering just a portion of highway funding to public transit would be transformational for the economy. You’d have enormous opportunities for people to get to their jobs, to doctor’s appointments, to expand the availability of affordable housing in high-demand areas.”

The rest of the world has “understood it’s important to move a lot of people easily to jobs and other places they need to go”, said Salerno. “But the US has prioritized suburban development and highway expansion, which has just induced more driving and given us choking traffic.”

Decades of decisions have led the US to this place. Since the interstate highway system was started in the 1950s, vast roads have laced the country – it’s possible to drive from Florida to Oregon, if you choose – and plowed into the heart of cities, severing communities and attracting traffic, prompting the widening of these highways, which then spurs even more traffic.

While other countries zipped ahead with high-speed rail, the US opted to link cities by highways and air travel. Zoning laws separated Americans’ amenities from places they live, resulting in sprawling suburbs that lack the sort of density where public transit works best, while businesses are routinely required to add voluminous car parking areas to their premises.

All of this means that American cities break from a pattern seen elsewhere in the world – when they expand, they don’t add new public transit, with trains and buses accounting for just 1.5% of total trips taken in the US. The cost of this car fixation is high – about 40,000 people a year die in car crashes, and drivers spend hundreds of billions of dollars to keep doing something that makes them unhappy, while emitting fumes that sicken those nearby and overheat the planet for everyone else.

“I think for most people, transportation is influenced by habit. People don’t even think about it,” said Watkins. “It actually shocks me when I meet someone who is focused on preserving the environment and community cohesion, and they’ve never even thought about how driving an automobile everywhere they go affects those things.”

While advocates have pushed, with some success in places, for more walkable, transit-available cities, the period since the pandemic has ravaged public transportation. Revenues for public transit systems nosedived as Covid-19 spread and then struggled to rebound as more people made a longer-term switch to working from home. Transit agencies in cities such as New York and Philadelphia have suffered major financial headaches.

The Trump administration, meanwhile, has turned sharply against public transport, depicting the New York subway as a nest of crime and attempting to kill off the city’s successful congestion charge for cars, which raises revenue for trains and buses. A spokesperson for Sean Duffy, the US secretary of transport, didn’t respond to the Guardian’s questions about public transport other than to address the issue of safety.

“Secretary Duffy is focused on making public transit safer for American families, and he has been on the forefront of calling out failed local leaders that have allowed their systems to fall into disarray,” he said. “Secretary Duffy wants to see American families benefit from cleaner and safer transit systems that run safely and efficiently.”

The administration has also attempted to slash federal transit funding and axed support for planned high-speed rail projects in California and Texas. The Texas proposal, which may still be completed by a private company, would be a 240-mile line connecting Dallas to Houston.

Currently, there is no train between the two cities, despite the uncomplicated route – instead there is an infrequent Amtrak train from Houston to San Antonio, a trip that takes about five hours (a similar distance is covered in half the time, over an international border, between London and Paris).

Polling shows most Americans would like better public transport options to help spend less time sitting in gridlocked traffic. Even in Harris county, home to Houston, where cars are used for the overwhelming majority of trips, voters approved a big upgrade to its Metro light rail and rapid bus system in 2019.

That plan has since been wound back by Houston’s mayor, who has taken to ripping up cycling and bus lanes, but the city still has an impressive, speedy light rail system at its heart. This network will be ramped up in the summer, when Houston hosts World Cup games and is inundated with fans from overseas who wouldn’t normally use a car to get to games.

Peter Eccles has lived without a car for a decade in Houston and admits some people are shocked when he divulges this. “I don’t think I’ve converted anybody to sell their car, but I’ve been able to explain how much money it’s saved me and how it’s removed a lot of stress from my life,” he said.

The World Cup will be an opportunity for “more Houstonians to find out that they like public transit very much and they’re going to expect that level of service to continue”, said Eccles, who is now policy director at Link Houston, a transit advocacy group.

Like in many US cities, though, traveling beyond downtown without a car becomes more challenging and can involve waiting with little shelter beside huge highways for several connecting buses that arrive frustratingly infrequently.

Soberingly, Houston would need to increase its fleet of buses and trains by 435% to have comparable levels of public transit with many European cities, the Transportation for America report found.

“This isn’t the best experience,” Eccles acknowledged as he got off the bus and was faced by an eight-lane highway with no pedestrian crossing. Cars rumbled past scenery of concrete, slowly baking in the sun, arranged into a tangle of flyover highways and strip malls. “OK, we are just going to have to cross here, quickly.”

Additional reporting by Ajit Niranjan