To what extent is U.S. state tax policy affected by corporate political contributions? The 2010 Supreme Court Citizens United v. Federal Election Commission ruling provides an exogenous shock to corporate campaign spending, allowing corporations to spend on elections in 23 states which...

We collect detailed data on U.S. state personal income, corporate, sales, cigarette, gasoline, and alcohol taxes over the past 70 years to shed light on the determinants of state tax policies. We provide a comprehensive summary of how tax policy has changed over time, within and across states....

We study a difference-in-differences (DiD) framework where groups experience unequal treatment statuses in the pre-policy change period. This approach is commonly employed in empirical studies but it contradicts the canonical model's assumptions. We show that in such settings, the standard DiD...