Three amendments prohibit discrimination based on a specified characteristic. The Fifteenth Amendment bars the United States and the states from denying or abridging a citizen's vote on account of race, color, or previous condition of servitude. The Nineteenth Amendment does the same for sex. The Twenty-Sixth protects citizens who are eighteen or older from denial or abridgment on account of age. Each amendment also gives Congress enforcement power. The wording is important: these provisions forbid a stated basis of exclusion; they do not create one identical national election system.

Formal protection was a beginning, not a self-executing finish. After the Fifteenth Amendment, discriminatory officials and private actors used literacy tests, white primaries, intimidation, violence, and selective registration to suppress Black voting. After the Nineteenth, women still faced barriers connected to race, citizenship, language, tax payment, location, and local administration. The Twenty-Sixth means that a government may not deny or abridge the vote of a citizen who is eighteen or older because of age. It does not require a state to exclude every younger citizen; a state may permit some people under eighteen to participate in specified elections under its own law. Young citizens who possess the right must still register and use an available voting method. A person can therefore be eligible while confronting a later obstacle in the election process.

Other reforms reached different barriers. The Indian Citizenship Act extended citizenship to Native Americans born in the United States, though state restrictions persisted. The Twenty-Fourth Amendment addressed poll taxes in federal elections. The Voting Rights Act supplied federal tools against racial discrimination. State reforms removed property qualifications and later broadened registration methods. The lesson is not that one amendment gradually solved everything. It is that separate rules attacked separate gates.

Do not use turnout as a test of whether a right mattered. Newly eligible citizens may initially receive little campaign contact, lack registration information, distrust institutions, or live where elections are not competitive. Parties and civic groups can respond over time, and participation can become habitual. Constitutional eligibility changes who may enter the process; registration, administration, mobilization, and political context help determine who actually does.

Video lesson: Voting rights | Political participation | US government and civics | Khan Academy