An article in the journal Environmental Health Perspectives, seeking to quantify benefits from reducing automobile usage for short urban and suburban trips, finds that reducing these short automobile trips and replacing them with active transport would yield major health benefits.  The authors estimate that, for the 11 metropolitan areas of the Upper Midwest, shifting 50% of short trips (less than 8 kilometers) to bicycle would yield a yearly savings of approximately $3.8 billion from avoided mortality and reduced health care costs, and the combined benefits of improved air quality and physical fitness would exceed $7 billion per year.