1 Department of Geography and Geoinformation Science, George Mason University, Fairfax, VA, USA. Electronic address: tleslie@gmu.edu.
2 Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
3 Center for Health Policy and Media Engagement, George Washington University School of Nursing, George Washington University, Washington, DC, USA; Department of Health Policy and Management, Milken Institute School of Public Health, George Washington University, Washington, DC, USA.