Sunday Streets are events that encourage recreation, community activities and fun in San Francisco. Sunday Streets closes stretches of city streets to automobile traffic, and opens them to people for several hours on a various Sundays throughout the year, so participants can enjoy a large, temporary, public space where they can bike, walk, run, dance, do yoga, or do any other physical activity. Non-profit and health organizations offer free activities and share information about their services during the event.
The information above can be found on the official website of Sunday Streets, a project of Livable City. For more details about the organization and to find out how you can volunteer, please visit their website: http://www.sundaystreetssf.com/volunteer