by a third in the last 40 years. This reduction has coincided with an increase in childhood obesity rates. The Centers for Disease Control and Prevention (CDC), in the USA, report that the prevalence of obesity among children has doubled and among adolescents has quadrupled in the past 30 years. In 2012, 18% of children and 21% of adolescents were obese. According to the Safe Routes to School National Partnership, 1 mile of walking equates to two thirds of the recommendation of 60 minutes a day. In addition to the potential health benefits, the walking school bus can help children arrive at school safely, on time, and ready to learn. Walking to school counts towards the recommended 60 minutes of physical activity a day. Another benefit is the positive association between physical activity and improved academic performance. In a study by the CDC, they found that with a minimum of 60 minutes a day there were increases in academic behavior, cognitive skills and attitudes. The communities that support walking buses may see reduced congestion around school grounds. The walking bus is a non-polluting and sustainable transport alternative to cars and buses. In regard to the safety of the walking bus, the section about Safe Routes to School below goes into more detail about improvements being made to increase the safety of commuting pedestrians. The built environment plays the biggest role in whether or not a community is walkable. The built environment consists of the human-made surroundings that affect one's life; including the availability and quality of sidewalks, crosswalks and parks, the amount of traffic and proximity to schools/parks/shops, etc. These factors determine the walkability of an area. Walkability has been shown to be closely tied to childhood obesity. One study found that “the chances of a child being obese or overweight were 20-60 percent higher among children in neighborhoods where it was not safe to walk around or where there were no sidewalks.” In addition, children in neighborhoods with sidewalks and safe places to cross the street are more likely to be physically active than children living in neighborhoods without those safe infrastructure elements. The walking bus depends on a walkable and safe built environment. Safe Routes to School is US government program that funds improvements in the built environment near schools. Support for the walking bus Health benefits Children who walk or bicycle to school have higher daily levels