During the debate over Voter ID, which I have endured ever since I began working in and around the Pink Building (about a decade now), photo ID requirements have been compared to poll taxes; the implication being that photo ID requirements would have a similar effect on turnout.
So, what were the effects of the poll taxes? In Texas, after the implemention of the poll tax, turnout dropped by over one-third (Wilkison, p. 169). In 1904, Cecil Lyon, a TX Republican leader, wrote to Theodore Roosevelt that “out of a colored population of some 650,000 not more than 25,000 qualified voters” (Barr, pp. 207-08). It should be noted that V.O. Key noted a sharp decline in Texas voter turnout began prior to the poll tax (Key, p. 534-35).