Each weekday morning, in large parking lots in the Washington, D.C., suburbs, hundreds of people stand in lines waiting for free rides to work from total strangers.
The practice, which famously began in the Washington area in the 1970s, is known as "slugging."
By taking on extra passengers, or "slugs," a Virginia driver can use the state's High Occupancy Vehicle (HOV) lanes, which can require up to three people per car.
For the last three decades, members of this underground suburban society have believed that everybody wins; the entire carload is ensured a traffic-free ride up notoriously clogged Interstates 95 and 395 to work at the Pentagon and other office buildings in Arlington, Va., and downtown Washington.
But, as gas prices continue to hit records, many slugs have noticed a sharp increase in their ranks, making for longer waits in line. And -- far worse -- they've detected a marked reduction in the number of drivers willing to give them a lift.
"I've noticed that it's harder and harder to get a ride," said longtime slug Kathy Ryan. "There's fewer cars picking up and more and more people in the line."
At a popular afternoon slug line, on 14th Street N.W. in downtown Washington, some slugs were seen waiting for nearly 30 minutes for a ride home.
Intermittently, a car with its hazard lights flashing could be seen crawling up to the curb. As many as two strangers would climb in before the car rolled off on its way to Virginia.
"It's getting hard now. This line used to be faster. Now, it's slowing," said Anna DeCosta.
Even a relatively new slug -- at it for just a year -- seemed upset that so many fellow travelers had joined him in line.
"They're all slugging 'cause they want to get to work easier, save gas money, have money for themselves," said Richmond Owusu.
Slugging began in the 1970s, amid the gas shortages caused by the Arab oil embargo and government price controls. The culture has thrived as the suburbs of the nation's capital have sprawled and gas prices have skyrocketed.
"There has been a resurgence of interest in slugging," said David LeBlanc, webmaster of www.slug-lines.com. "Those that may have dismissed it in the past as a crazy way of commuting now are looking at it as an alternative."
Hits on the Web site, which hosts discussions on the unique rules of slug culture along with maps of pickup locations, have increased "dramatically" as oil and gasoline prices have spiked, according to LeBlanc.
LeBlanc, who slugs regularly from his home in Woodbridge, Va., to his office in Arlington, says he has not personally noticed longer waits at his slug lines. But he wouldn't doubt that it's been true for others.
"If I were to drive in, it's about a $16 to $20 decision, just in gas alone. Other folks that may have to drive an even further distance may look at that and say, 'Well, maybe I should start slugging as opposed to driving,'" LeBlanc said.
Across the country, other ride-sharing Web sites also have noticed an increase in traffic as gasoline nears $4 per gallon.
Steve Schoeffler, of www.eRideShare.com, says traffic on his site has more than doubled in the last few months.
"We've seen a substantial shift in the intensity of the people using the site. They're more determined. There are more contacts being made," Schoeffler said.
Recently, posters began a heated discussion on www.slug-lines.com over whether, after decades, slugs should now be expected to pitch in for the cost of gas.
"Let's be fair to our fellow drivers so we can all continue to benefit from this amazing system," wrote "sandy," who suggested a dollar per ride.
But she was lambasted by fellow slugs. One suggested that drivers who pick up paying slugs should be licensed as a taxi service and that the IRS should tax the income.
LeBlanc also leans against cost-sharing.
"The rules of slugging are: The driver bears the costs. The slugs do not share in the cost. It would be very, very hard to determine what would be a fair and appropriate reimbursement to the driver," he said.
Longtime slug Erick Erickson of Burke, Va., wasn't sympathetic to the drivers who give him free rides, noting that he often drives slugs.
"This is the marketplace. If someone feels like it's not fair, they don't have to stop. There's no compulsion here," he said.