Be extra careful out there today, folks! It's the 3rd Annual Bike to School Day, in which approximately 3,000 students at more than 40 schools throughout town will be pedaling to school and back. Bay City News via SF Appeal reports that several San Francisco supervisors will be coming along for the ride, including Eric Mar, David Chiu, Jane Kim, Carmen Chu, John Avalos, and Scott Wiener.

Fifteen San Francisco schools participate in the yearlong Safe Routes to School program, encouraging families to bike and walk to school daily. The San Francisco Bicycle Coalition says that the majority of the students live within a mile of the participating schools, and San Francisco Unified School District is working to install bike racks at all the schools in the city.

As the Bike to School Day site notes:

If the number of kids who walk and bike to school was restored to 1969 levels, our nation would cut 3.2 billion vehicle miles, 1.5 million tons of CO2, and 89,000 tons of other pollutants annually. This is the equivalent of keeping more than 250,000 cars off the road for a year.

- Pedroso, M., 2008, Safe Routes to School: Steps to a Greener Future

Read some endearing stories about kids and their families who are participating in the event over at SF Bike Coalition.