It can be tough to get Americans to use mass transit. See the case of Los Angeles: billions have been spent in recent years and use is down.

The Los Angeles County Metropolitan Transportation Authority, the region’s largest carrier, lost more than 10% of its boardings from 2006 to 2015, a decline that appears to be accelerating. Despite a $9-billion investment in new light rail and subway lines, Metro now has fewer boardings than it did three decades ago, when buses were the county’s only transit option.

Most other agencies fare no better. In Orange County, bus ridership plummeted 30% in the last seven years, while some smaller bus operators across the region have experienced declines approaching 25%. In the last two years alone, a Metro study found that 16 transit providers in Los Angeles County saw average quarterly declines of 4% to 5%…

The decline suggests that Southern California policymakers are falling short of one of their longtime goals: drawing drivers out of their cars and onto public transportation to reduce traffic congestion, greenhouse gases and the region’s reliance on fossil fuels…

Southern California certainly isn’t alone. Public transportation use in many U.S. cities, including Chicago and Washington, D.C., has slumped in the last few years. But the question takes on new significance in Los Angeles County, where politicians and transportation officials are considering whether to seek another half-cent sales tax increase in November that could raise $120 billion for major transportation projects, including several new rail lines.

Cheap gas is not helping. I’ve been thinking in recent days that if there was any time to increase gas taxes to provide needed money for roads and other transportation projects, now is the time.

More broadly, most Americans seem to want to drive themselves when they can. Even though the total costs of owning a car add up, driving offers status and freedom. In a society where those are two key values, mass transit may not be able to compete when there isn’t the kind of density found in New York City or San Francisco.