There is a paucity of research examining associations between walking and environmental attributes that are more modifiable in the short term, such as car parking availability, access to transit, neighborhood traffic, walkways and trails, and sidewalks. Adults were recruited between April 2004 and September 2006 in the Minneapolis-St Paul metropolitan area and in Montgomery County, Maryland using similar research designs in the two locations. Self-reported and objective environmental measures were calculated for participants' neighborhoods. Self-reported physical activity was collected...