State preemption, smoke-free law strength, and local laws: associations with U.S. cigarette purchases, 2004–2021

Background State preemption on local tobacco control may have negative population-level impacts. However, limited empirical research has examined these impacts over time across all states or considered their impact within the context of other state and local laws. This study assessed state preemption, state smoke-free law strength, and local smoke-free laws in relation to cigarette purchases over ∼18 years.Methods State smoke-free workplace preemption, state smoke-free law strength (number of settings covered, CDC’s STATE System), and local smoke-free laws (American Nonsmokers’ Rights Foundation) were assessed in relation to cigarette purchases (NielsenIQ consumer panel [2004–2021] and retail scanner panel [2006–2021]). Analyses (accounting for county-level sociodemographics) explored interactions between preemption and state law strength.Results In both datasets, preemption, weaker state smoke-free laws, and lack of local laws were associated with more purchases; interactions indicated that preemption vs. non-preemption states with weaker smoke-free laws showed more purchases. The consumer panel also showed that stronger vs. weaker state smoke-free laws were associated with fewer purchases and were particularly important in preemption vs. non-preemption states.Conclusion Strong state and local smoke-free laws are essential tobacco control tools. Preemption may have particularly detrimental impacts when state smoke-free laws are weak, underscoring the need to limit preemption.