The fail-safe for many voters who run into problems at the polls — such as a lack of ID or an outdated address — is called provisional voting. The person votes, and his or her ballot only counts after the problem is resolved.
But many of these ballots never do count, raising questions about how good a fail-safe they really are.
In Virginia, for example, some residents have been preparing to meet a new state requirement that all voters show a photo ID at the polls. Bernest Sellars, 87, is one of several elderly voters who lined up recently to get a new ID at a senior center in Arlington.