A new report from UCLA blames a dramatic increase in car ownership across Southern California for the region’s free-falling transit ridership.

“The overwhelming factor is that, from 2000 to 2015, the region added a lot of automobiles,” says Michael Manville, assistant professor of urban planning at UCLA.

Manville co-authored the report, which was prepared for the Southern California Association of Governments and released today.

The report’s authors acknowledge that it’s hard to pin down a single reason why transit ridership is dropping, but they ultimately conclude more Angelenos have access to cars than ever before.

From 2000 to 2015, the six-county study region—Los Angeles, Orange, Riverside, San Bernardino, Ventura and Imperial counties—added 2.3 million people and 2.1 million household vehicles. Compare that to the decade prior, when, from 1990 to 2000, the area added 1.8 million people, but only 456,000 cars.

Sign up for the Curbed LA Newsletter Email (required) By signing up, you agree to our Privacy Notice and European users agree to the data transfer policy. Subscribe

In other words, Southern Californians purchased cars at a rate four times higher than they did during the 1990s. Manville says the rate of car-ownership increased disproportionately among the predominantly poor and foreign-born, demographics that are most likely to ride transit.

Despite Metro’s huge investment into the expansion of LA’s transit network, ridership keeps declining year after year—and 2017 was no exception.

Last year, ridership dropped 4 percent below its 2016 levels, Metro data shows. Compared to just five years ago, there were nearly 17 percent fewer boardings systemwide in 2017.

The report’s authors say that that if a person has easy access to a car, it’s highly unlikely they’ll ride transit. As more people gain access to personal vehicles, transit ridership suffers.

The UCLA report is the first to crunch the numbers for Southern California. The report also considers other factors, including the rise of ride-share companies, the level of service provided by transit operators, perceived personal safety aboard buses and trains, and even gentrification-driven displacement along dense transit corridors.

Folding in statewide transit data, the authors determined that Metro—the operating agency for public transit across Los Angeles County—alone accounted for 72 percent of transit losses statewide since 2012.

Most of Metro’s ridership loss is highly concentrated to just a few transit routes, especially bus routes, through dense central Los Angeles. As the report says, “a dozen routes from LA Metro account for 38 percent of all the lost ridership in California.”

The UCLA authors weren’t able to conclusively link gentrification-driven displacement in central Los Angeles to ridership loss—the data needed to draw such a conclusion isn’t readily available—but they did say there are plenty of indicators that show such neighborhood change might be linked transit declines. The topic, they say, “warrants substantial further research.”

The lion’s share of Metro’s ridership loss is taking place aboard the agency’s bus system, but almost every rail line in LA County is also seeing similar declines.

Though the Expo and Gold Lines, bolstered by recently opened extensions, each saw ridership increases between 2012 and 2016, ridership declined aboard most of Metro’s rail lines, including the Red, Blue, and Green lines, enough to erase the gains made on the Expo and Gold lines.

Overall, the report concludes that, going forward, the best strategy to recapture lost ridership might be to refocus on trying to encourage the 77 percent of Southern Californians who seldom, if ever, use transit, to ride occasionally.

As the report details, dedicated “transit commuters,” defined as those who ride public transit 44 to 49 times per month, make up about 25 to 30 percent of all transit trips, though they make up only about 2 to 3 percent of the region’s population.

Though “transit non-commuters” ride less than transit commuters—about 11 to 16 times per month—they actually account for more than half of all Southern California trips because there are many more (about 20 to 23 percent of the region’s population) of them than there are transit commuters.

“Infrequent transit users,” those who ride rarely or never, are about three-quarters of Southern California’s population. Even though they seldom ride, their large population means that about 16 to 18 percent of transit trips come from this group.

“If one out of every four of those people replaced a single driving trip with a transit trip once every two weeks, annual ridership would grow by 96 million—more than compensating for the losses of recent years,” the report’s authors conclude.