Pennsylvania voters will not have to show photo identification to participate in Tuesday's primary election, according to state election officials.

Though the legislature passed a law last year requiring state residents to show identification to vote, several groups have challenged the constitutionality of the new law in court.

A judge ruled last year that the state had not given voters sufficient warning about the change, and postponed implementation until sometime after the November 2012 general election.

However litigants in the lawsuit agreed in February to extend that postponement beyond the May 21 primary election, meaning voters will be asked to show photographic identification, but will not be turned away from the polls if they do not produce an ID.

Secretary of the Commonwealth Carol Aichele urged voters to cast ballots in next Tuesday's primary election and reminded voters they will again be asked, but not required, to show photo ID at the polls.

"This will be the third straight election in which voters will be asked, but not required, to show photo ID at the polls, as part of our continuing education efforts about Pennsylvania's Voter ID law," said Aichele, whose department oversees elections.  "Poll workers will give voters without acceptable photo ID information on what IDs are acceptable for voting and how to get a free ID for future elections."

Aichele reminded first time voters, and those casting ballots for the first time at a new polling place, they must show either a photo ID, such as a PA driver's license, or a non-photo ID with the voter's name and address, such as a utility bill.

As part of the Voter ID law, voters using absentee ballots must include either their PA driver's license number or the last four digits of their Social Security number on their application, as was the case in last November's election.

If you're between the ages of 18 and 24, chances are you registered to vote when you visited the Department of Motor Vehicles. If you're over the age of 65, you probably registered to vote at some other government office.

Those are the findings of a new Census Bureau survey that asked Americans how they registered to vote. As it turns out, younger voters are much more likely to register when they get a driver's license, at their school or university campus, or online.

Contrary to popular belief, which suggests same-day voter registration overwhelmingly helps younger voters -- particularly college students -- sign up to cast a ballot, it turns out that a higher percentage of seniors register on Election Day than younger voters. More than seven percent of voters over the age of 65 said they had registered on Election Day, compared with 5.3 percent of voters between the ages of 18 and 24.