INTRODUCTION: Public health advocates have expressed concern about state preemption laws limiting local government's ability to regulate tobacco smoking. However, empirical evidence on these laws' impact is scarce. This study examines how repealing such laws impacts policies covering smoke-free indoor air. METHODS: Policy data were obtained from the Americans for Nonsmokers' Rights Foundation's smoke-free laws database (1990-2022), analyzed in 2024. A two-way fixed effects model in multiple linear regression was employed to evaluate the relationship between the repeal of smoke-free indoor air preemption statutes and the proportion of the state population covered by smoke-free policies. Additional analyses were conducted using alternative control groups, and the fractional form of the dependent variable was accounted for in the study. RESULTS: Results revealed that the repeal of smoke-free indoor preemption was related to an increase in the probability of the state population covered by smoke-free indoor air policies in the baseline model (β=0.405, p<
0.01), analysis with two-way fixed effects (β=0.199, p<
0.01), and the analysis incorporating state-unique time trends to the two-way fixed effect model (β=0.327, p<
0.01). Similarly, the fractional probit regression results showed that repealing state preemption laws corresponded to an increase in the probability of smoke-free indoor air policy coverage. The average marginal effects ranged from 0.19 to 0.43. The results were consistent in analyses that included only states that had preemption laws at any point. CONCLUSIONS: Repealing state tobacco preemption laws could broaden local policies covering smoke-free indoor air, potentially mitigating secondhand smoke risks and lessening tobacco's health and economic burdens.