What Really is the Growth of Vehicle Usage?

The enormous jump in vehicle miles traveled (VMT) per person reported by the 1990 Nationwide Personal Transportation Survey (NPTS) conducted by the U.S. Census Bureau caused a great deal of concern among planners and policy analysts. Such a jump seemed to portend an era of ever-increasing travel, pollution, and energy consumption. Three alternative VMT estimates are developed using data from other national surveys and a massive odometer-based California study. The three new estimates are nearly identical but differ markedly from the NPTS results. (Reanalysis of the 1990 NPTS shows that it oversampled new vehicles: since new vehicles are driven two to three times as much as old ones, VMT per average vehicle is overestimated.) VMT per vehicle actually grew at only half the rate estimated by the NPTS.