Rails to Trails http://www.railstotrails.org/
East Coast Greenway http://www.greenway.org/
Pennsylvania Environmental Council http://www.pecpa.org/southeast-pa-regional-trail-network
Del. Valley Reg. Planning Commission http://www.dvrpc.org/
Friends of the Wissahickon http://www.fow.org/
Bicycle Coalition of Greater Philadelphia http://www.bicyclecoalition.org/
Schuylkill River Trail http://www.schuylkillrivertrail.com/
Complete the Trails completethetrails.org
Centers for Disease Control Obesity Trends http://www.cdc.gov/obesity/data/trends.html