What protections do voters get from constitution?

The term originated in late nineteenth-century legislation and constitutional amendments passed by a number of U.S. southern states, which created new requirements for literacy tests, payment of poll taxes, and/or residency and property restrictions to register to vote. States in some cases exempted those whose ancestors (grandfathers) had the right to vote before the civil war, or as of a particular date, from such requirements. The intent and effect of such rules was to prevent poor and illiterate African-American former slaves and their descendants from voting, but without denying poor and illiterate whites the right to vote