Often, such a provision is used as a compromise or out of practicality, to allow new rules to be enacted without upsetting a well-established logistical or political situation.
The term originated in late 19th-century legislation and constitutional amendments passed by a number of Southern U.S. states, which created new requirements for literacy tests, payment of poll taxes and residency and property restrictions to register to vote.
States in some cases exempted those whose ancestors (e.g., grandfathers) had the right to vote before the American Civil War or as of a particular date from such requirements.
After Democrats took control of state legislatures again, especially after the Compromise of 1877, they began to work to restrict the ability of black people to vote.
Nonetheless, a coalition of Populists and Republicans in fusion tickets in the 1880s and 1890s gained some seats and won some governor positions.
The 1965 Voting Rights Act had provisions to protect voter registration and access to elections, with federal enforcement and supervision where necessary.