Trends in Automobile Travel, Motor Vehicle Fatalities, and Physical Activity: 2003-2015

Annual per-capita automobile travel declined by 600 miles from 2003 to 2014 with decreases greatest among young adults. This article tests whether the decline has been accompanied by public health co-benefits of increased physical activity and decreased motor vehicle fatalities.

Minutes of auto travel and physical activity derived from active travel, sports, and exercise were obtained from the American Time Use Survey. Fatalities were measured using the Fatality Analysis Reporting System. Longitudinal change was assessed for adults aged 20-59 years by age group and sex. Significance of changes was assessed by absolute differences and unadjusted and adjusted linear trends. Analyses were conducted in 2016.

Daily auto travel decreased by 9.2 minutes from 2003 to 2014 for all ages (p<0.001) with the largest decrease among men aged 20-29 years (Δ= -21.7, p<0.001). No significant changes were observed in total minutes of physical activity. Motor vehicle occupant fatalities per 100,000 population showed significant declines for all ages (Δ=-5.8, p<0.001) with the largest for young men (Δ= -15.3, p<0.001). Fatalities per million minutes of auto travel showed only modest declines across age groups and, for men aged 20-29 years, varied from 10.9 (95% CI=10.0, 11.7) in 2003 to 9.7 (95% CI=8.7, 10.8) in 2014.

Reduced motor vehicle fatalities are a public health co-benefit of decreased driving, especially for male millennials. Despite suggestions to the contrary, individuals did not switch from cars to active modes nor spend more time in sports and exercise. Maintenance of the safety benefits requires additional attention to road safety efforts, particularly as auto travel increases.