Our Study, Examining the Impact of Food Deserts on Public Health in Chicago, included a robust, albeit self-reported, sample of height and weight from driver’s license records by Zip Code. Height and weight, included in those records, allows the calculation of body mass index (BMI), an accepted measure for obesity. The data are grouped into tertiles (thirds). The map shows a striking clustering pattern: Chicago’s North and Northwest sides have the lowest rates of BMI and the West and South sides have the highest rates of BMI.