The amount of public green space in cities around the globe temporarily expands every year on September 18 as activists reclaim metered parking spots by converting the paved plots into temporary parks. The PARK(ing) Day movement was started in 2005 by Rebar, a San Francisco art collective, and has since grown into an annual event celebrated by diverse organizations. PARK(ing) Day participants pay "rent" at the parking meter, then decorate their space with sod, sand, potted plants, or lawn furniture. Many groups build their temporary parks to advocate for the creation of permanent community spaces, but messages about clean energy, green transportation, and sustainable cuisine have also been communicated through the project. Watch the video above to learn about parks created during the 2006 event or check out the PARK(ing) Day Flickr group to view snapshots of this year's turnout.