“…First, for the introduction of the income tax, Penniman (1980) verified institutionally that the reasons were largely idiosyncratic and political, and that states had other ways to raise revenues. Cassidy, Dincecco and Troiano (2017) conduct an additional robustness check. They look at how close the vote to introduce the income tax was, and they split the sample in places where the vote was close, and places where the vote was not close.…”