National Renewable Energy Lab, Oct. 19, 2016.
http://www.nrel.gov/news/press/2016/38755

"...[NREL] recently examined the carbon abatement potential of city actions in six policy areas as part of the DOE's Cities Leading through Energy Analysis and Planning (Cities-LEAP) project. The analysis uses new data on energy use in more than 23,400 U.S. cities and estimates the aggregate impact of city actions related to: building energy codes, public transit, building energy incentives, rooftop photovoltaics, smart growth, and municipal actions."