Adding an extra layer of ID requirement at the polls evokes unpleasant and problematic historical memories for many people in the U.S.

Legal and political framework governing who may vote in the United States and how, covering the Voting Rights Act, constitutional amendments and the litigation over registration, purges and district maps. Access and integrity are the two poles the argument moves between.

Rules requiring voters to present identification before casting a ballot, which vary widely between states in strictness, accepted documents and enforcement. Defended as a safeguard against fraud and challenged as a barrier for voters without a driving license or fixed address.