Factors contributing to the slowdown:
•Soaring gas prices. Seven of 10 Americans are combining trips and taking other steps to reduce driving, according to a USA TODAY/Gallup Poll taken May 4-6. Don Harrison, 32, of Indianapolis, no longer visits his relatives across town on the weekend; he saves gas by simply calling them.
•Expanded public transportation. More people took public transit last year than at any time in 49 years. "We're seeing suburban locations create new transit systems," says William Millar, president of the American Public Transportation Association. "They're expanding into areas that never thought they needed transit because they could do everything by car."
•Slower growth of minority and women drivers and the aging of the population. Except for African-Americans, minority groups drive at high rates, and the annual growth in women drivers has slowed, says Alan Pisarski, an expert on commuting patterns. Also, he says, people on average drive less after age 55.
•Demographic shifts that de-emphasize the need to drive. Many Americans, particularly young, upwardly mobile singles, are moving downtown and revitalizing cities. "(They) don't have to live the way of the Ozzie and Harriet model — two parents, suburban, who drive to the city," McMahon says.