US cities have a staggering problem of Kia and Hyundai thefts. This data shows it.

Chicago used to have about 850 cars stolen per month. Now, it consistently has more than 2,000, an average of 86 cars stolen every single day. Denver rarely had more than 800 stolen cars in a month before 2021. Now it usually has more than 1,000. Atlanta usually had less than 250 per month before 2022. This year, it has doubled.

The thefts are centered around two car brands: Kia and Hyundai. The companies sold more than nine million cars over the course of a decade without basic anti-theft technology that makes them trivially simple to steal.

From 2011 to 2021, Kia and Hyundai manufactured many of their cars, including almost all of their lower-end models, without engine immobilizers, a basic anti-theft device that costs about $100 to manufacture into a car and prevents them from being hot-wired. Anti-theft devices are required by law in Canada, but not in the U.S. The rest of the car industry widely adopted immobilizers, and Kia and Hyundai use them in Canada and Europe. But in the U.S, just 26 percent of Kias and Hyundais had immobilizers as late as 2015. In total, some nine million vehicles in the U.S. are vulnerable.

This fact, combined with the emergence of a subculture dubbed the Kia Boys or Kia Boyz that turned stealing the cars into sport, has resulted in a stolen car crime wave unlike anything the U.S. has seen in generations. Stolen car rates are not up by 10 percent, or 20 percent, or even 50 percent. In many cities, they are up hundreds of percentage points, Motherboard has found. Rates of stolen Kias and Hyundais in particular are up thousands of percentage points.

And, so far, according to data obtained by Motherboard via public records requests, efforts by both the manufacturers and police to slow the wave appear to be largely ineffective.

Equipped with only a screwdriver and a USB cord and watching one or two tutorials, pretty much anyone can steal a Kia or Hyundai without an immobilizer. In several lawsuits filed by U.S. cities against Kia and Hyundai, plaintiffs allege the thefts are mostly done by teenagers, some too young to legally drive, for joyriding, crashing, vandalizing, or in some cases to then commit other crimes.

The scale of the Kia and Hyundai theft problem is astounding. In Chicago, during the “old normal” days prior to the summer of 2022, six to eight percent of all stolen cars were Kias or Hyundais, according to data obtained by Motherboard. This was in line with how many Kias and Hyundais were on Chicago’s roads, according to the lawsuit Chicago filed against Kia and Hyundai. Then, in June 2022, the percentage of stolen cars that were Kias and Hyundais edged up to 11 percent. In July, it more than doubled to 25 percent. By November, it had almost doubled again, to 48 percent. Through August 2023, the most recent month for which Motherboard has data, 35 percent of the 19,448 stolen cars in Chicago have been Kias or Hyundais.

The trend of Kias and Hyundais becoming a large proportion of a city’s stolen vehicle fleet is almost universal. In Denver, Kias and Hyundais went from about seven percent of all stolen vehicles in 2020 to an average of 26 percent the two years afterwards. Only 57 Kias and Hyundais were stolen in Denver in July 2020. Two years later, 464 were stolen, a 714 percent increase.

In Atlanta, a whopping 64 percent of the stolen cars in May 2023 were Kias and Hyundais, up from just six percent a year earlier.

According to a lawsuit filed by the city of Columbus, attempted annual Hyundai and Kia thefts increased 21,400 percent (from four to 860) in just one year. Actual thefts increased 494 percent. A public records request with Columbus for more detailed data has not yet been fulfilled.

Even Chicago’s surge can’t compare to what happened in Milwaukee, which is largely cited as the epicenter of the trend. According to a lawsuit filed by the city, Kia-Hyundai thefts increased 2,500 percent in June 2021 versus a year prior. In September of that year, more than 5,100 Kia-Hyundais were stolen, more than two-thirds of all stolen cars in the city. Through mid-2023, Kia-Hyundais still made up 52 percent of all car thefts, although the overall number of stolen cars has declined about 30 percent from its peak.

Still, there are important differences in how the theft trend is—and isn’t—spreading. Some cities are getting hit harder than others for reasons that aren’t clear. For example, San Diego has had only a modest increase in Kia and Hyundai thefts, relatively speaking, amounting to a couple dozen additional stolen cars a month. The same is true of Fort Worth, Texas and Bakersfield, California. Tulsa wasn’t able to provide Motherboard with any data because their systems are still recovering from a hack that prevents them from tabulating such data, according to Lieutenant Chase Calhoun of the auto theft unit, but he said their most stolen vehicles remain Ford F-150 and Chevy Silverado pickups.

Perhaps the most interesting outlier from the dataset so far is Denver, which saw an early, sustained, and relatively gradual increase in Kia-Hyundai thefts throughout 2020, 2021, and 2022. This is in contrast to most other cities that saw sharp spikes within a period of a few months more indicative of an online fad.

When Motherboard asked if they had any theories why this was, a spokesperson for the Denver Police Department said, “Anecdotally, we do believe social media videos contributed to the increase in Hyundai and Kia thefts in Denver, but it’s difficult to know the extent of that influence on these crime trends. We also believe the social media videos encouraged young people who wouldn’t otherwise try to steal a car, to do just that.”

If this is true, it would be a problematic development for cities. Some criminologists believe auto theft is what they call a “keystone crime,” which encourages and facilitates other crimes. Local news reports in pretty much every affected city refer to crashes, robberies, and deaths involving stolen Kias and Hyundais. In a court filing, Minnesota Attorney General Keith Ellison said that last year, “thefts of Hyundai and Kia vehicles were tied to at least 5 homicides, 13 shootings, 36 robberies, and 265 motor vehicle collisions” and nine people died in reckless driving crashes involving the vehicles, all of which was in Minneapolis alone.

Videos of these crimes are easy to find on social media. Many of the videos are posted under burner accounts with handles that begin with the city’s area code followed by some version of “Kia Boys”, “Kia Boyz,” “Hyundai Boys,” and so on.

The vast majority of the hundreds of accounts reviewed by Motherboard have less than a hundred followers, and most of their posts have single or low double-digit likes. Most of the videos show people driving cars, often erratically, swerving repeatedly, accelerating quickly, and otherwise joyriding.

However, a tutorial from an account with a Fort Worth area code went viral with more than 11,000 likes. And several accounts with Milwaukee and Minneapolis area codes regularly rack up tens of thousands of likes on their posts. Instagram did not respond to a Motherboard request for comment. A TikTok spokesperson said the platform’s community guidelines don’t allow “any violent threats, incitement to violence, or promotion of criminal activities that may harm people, animals, or property” and they encourage users to report potential violations.

At first, the companies tried to sell an aftermarket anti-theft device through their dealer network for $170 plus labor to install. Starting in February, Kia and Hyundai released software updates the companies say provide an “ignition kill” feature that ought to prevent theft, provided free steering wheel locks, and partnered with AAA insurers because many insurance companies stopped selling policies for the affected vehicles.

About two million of the nine million vehicles vulnerable to theft cannot receive the software update. As of July, Carfax reported about five million vehicles still remained vulnerable to theft either because they hadn’t gotten the software update or were not eligible. But there have been reports in Buffalo and Washington, D.C. of vehicles with the software update still being stolen.

Louisville hit a new record of stolen Kias and Hyundais (335) in July, 53 percent of all vehicles stolen in the city. San Diego and Sacramento have also experienced record-high Kia and Hyundai thefts in recent months. So have Fort Worth and Atlanta.

When asked why the cars keep being stolen in record numbers despite the software update, a Hyundai spokesperson says the company has upgraded “almost a million vehicles” with the software update and “have not seen any confirmed failures of the software. It is working as designed.” After this story was first published, a Kia spokesperson told Motheboard, “We remain confident the software upgrade we developed works to combat the method of theft popularized on social media and further enhance the vehicle’s security by restricting the operation of the ignition system while the vehicle is locked and the alarm system is armed.”