The Robert Wood Johnson Foundation released a report with interactive maps on February 17, 2010, that ranks the overall health of each county in the U.S.  County health rankings were determined by the residents' lifespan and their overall health.  Counties were ranked on a variety factors that affect health – including air pollution levels and the built environment.  These factors, as they relate to Transportation infrastructure and facilities, can promote or discourage active, healthy modes of travel such as biking and walking.