More than a dozen states plus the District of Columbia now offer same-day registration (SDR), allowing qualified residents to go to the polls or an election official’s office, before or on Election Day, register to vote, and then cast a ballot, all on the same day.

In most states, voters must register well before Election Day. The deadline varies, with states requiring registration eight to 30 days before the election.

Maintaining a period between registration and voting allows election officials time to verify the qualifications and residency of the voter, thus reducing the opportunity for vote fraud. Once an unverified and unqualified voter casts a ballot and it is counted, there is no way to go back and disqualify the illegally cast ballot.

Combining registration and voting on the same day causes long lines and unnecessary chaos on a day when millions of people are voting. The congestion caused by same-day registration can overwhelm poll workers and create long lines for registered voters. Same-day registration provides unnecessary pressure on local election officials who are responsible for providing up-to-date voter registration lists to each polling place.

As Wisconsin Gov. Scott Walker observes, “States across the country that have same-day registration have real problems because the vast majority of their states have poll workers who are wonderful volunteers, who work 13-hour days and who in most cases are retirees,” he said. “It’s difficult for them to handle the volume of people who come at the last minute. It’d be much better if registration was done in advance of Election Day. It’d be easier for our clerks to handle that.”

The unverified registration process favors those political candidates who can round up otherwise indifferent citizens who know little about what’s on the ballot. An informed citizenry is the bulwark of a constitutional, democratic republic.