To save wear&tear on the browsers;
a) 17th Amendment (1913) - Direct Election of the US Senate by popular vote superseding Article I, §3, Clauses 1 and 2 of the Constitution, by which US Senators were elected by state legislatures. Could be considered a death knell of true Federalism as it diminished power of the States in the Federal Government.
b) 19th Amendment (1920) - Women's right to vote. Another power grab by the Federal Government over the various States that were given the right to determine internal voting standards. No matter how much one may agree with the intent, from this precedent comes the Federal ability to mandate law within the States.
c) 24th Amendment (1966) - Prohibits both Congress and the states from limiting the right to vote in federal elections to require payment of a poll tax or other types of tax. Also has been extended by court cases, on the same principal to literacy and knowledge testing. Again flowing from the preemption of State Sovereignty as in the previously mentioned. While extensively used by the former Confederate States to depress minority voting, its implementation also paves the way to enabling the Welfare state to continue voting for increased benefits.
Yeah but that ruins the (for me running) joke when they look up the 19th :)