The Impact of a Sweetened Beverage Tax on Beverage Volume Sold in Cook County, Illinois, and Its Border Area

Background: Sugar-sweetened beverage (SSB) consumption is linked to adverse health outcomes. Objective: To evaluate the impact of the 2017 Cook County, Illinois, Sweetened Beverage Tax (SBT) on the volume of taxed and untaxed beverages sold in Cook County and its 2-mile border area. Design: Pre-post intervention-comparison site difference-indifferences study. Setting: Cook County, Illinois, and St. Louis City and County, Missouri, 2016 to 2017. Participants: Universal product code-level store scanner data from supermarkets and grocery, convenience, drug, mass merchandise, and dollar stores. Measurements: Beverage volume sold of taxed and untaxed beverages, across product categories and sizes. Results: Volume sold of taxed beverages decreased by 27% (ratio of incidence rate ratios [RIRR], 0.73 [95% CI, 0.70 to 0.75]) on average in Cook County relative to St. Louis during the 4 months that the SBT was in effect (compared with the same 4-month pretax period), with a net decrease of 21% after in-creases in volume sold in its border area (cross-border shopping) were taken into account. The magnitude of the decrease in volume sold across types of taxed beverages was heterogeneous: -32% (RIRR, 0.68 [CI, 0.65 to 0.72]) for soda versus -11% (RIRR, 0.89 [CI, 0.82 to 0.97]) for energy drinks, -37% (RIRR, 0.63 [CI, 0.59 to 0.66]) for artificially sweetened beverages versus -25% (RIRR, 0.75 [CI, 0.72 to 0.79]) for SSBs, and -29% (RIRR, 0.71 [CI, 0.68 to 0.74]) for family-size versus -19% (RIRR, 0.81 [CI, 0.79 to 0.84]) for individual-size beverages. There was no significant change in volume sold of untaxed beverages in Cook County or its border area. Limitation: Data source did not allow for evaluation by store type or distance of outlets from the border. Conclusion: The Cook County SBT led to a substantial reduction in the volume sold of taxed beverages in Cook County. Part of this effect was offset by cross-border shopping. Cross-border shopping was limited to tax avoidance and did not extend to untaxed beverages.