dec 13, 1965 - Voting Rights Act of 1965
the 23rd and 24th amendment stem from the voting rights act. The 23rd amendment (passed in 1961) added the voters of the District of Columbia to the presidential electorate. The 24th amendment (ratified in 1964) eliminated the poll tax as a condition for voting in any federal election.
Added to timeline:
History of the right to vote
5 States of Extending Suffrage