Besides intimidation, there were three different methods used in southern states in the early part of the century to disenfranchise black citizens: 1) the poll tax; 2) literacy tests; and 3) grandfather clauses. The poll tax required a voter to pay a fee in order to exercise the right to vote. Literacy tests were implemented as a prerequisite for voting; this method also kept many poorly educated whites (unable to pass the exam) from casting their ballots as well. Most southern states also adopted legislation by which voting rights were extended only to those citizens who had been able to vote as of a certain date—a date when few if any black men would have been able to vote. Since these laws made provisions for said voters’ descendants as well, they were dubbed “grandfather clauses.” Such attempts to deny citizens the right to vote were made unlawful in 1964 (by the Twenty-fourth Amendment, which outlaws the poll tax in all federal elections and primaries), in 1965 (by the Voting Rights Act, which outlawed measures used to suppress minority votes), and in 1966 (when poll taxes at the state and local levels were also declared illegal). Literacy tests and grandfather clauses were also struck down as unconstitutional.