1 Texas Center for Geographic Information Science, Department of Geography and Environmental Studies, Texas State University, San Marcos, TX 78666 (zhan@txstate.edu).
2 Cancer Prevention and Control Program, LiveStrong Cancer Institutes, Dell Medical School, University of Texas at Austin.
3 Department of Population Health, Dell Medical School, University of Texas at Austin.
4 Texas Center for Geographic Information Science, Department of Geography and Environmental Studies, Texas State University, San Marcos, Texas.
5 Department of Internal Medicine, Dell Medical School, University of Texas at Austin.
6 University of Texas at Austin, LBJ School of Public Affairs, Austin, Texas.
7 Texas Association of Community Health Centers, Austin, Texas.