Carpooling has been in a bit of a slump these past, oh, 30 years. In 1980, about one in five commuters carpooled to work, according to the latest Commuting in America report compiled by the American Association of State Highway and Transportation Officials. By 2010 that figure was down to one in 10. Steven Polzin, one of the report's coauthors, calls the steep decline in carpooling "the most significant change in commuting behavior in the past few decades."
Any numbers of factors could explain carpooling's fading glory. Metro areas have more job centers than in the past. Work schedules are more flexible, and telecommuting is on the rise. Above all, driving to work alone remains a cheap and convenient option, with employers subsidizing parking and a policy focus on highway expansion draining HOV lanes of their power.