By endorsing Proposition 200, Arizona voters might have unwittingly put the stamp of approval on a growing Election Day trend: mail voting. A top Pima County election official expects more voters to rely on the U.S. Postal Service rather than deal with the bother of making sure they have proper identification when they show up at the polls. "People will not want the hassle," said Pima County Recorder F. Ann Rodriguez. Prop. 200, the anti-illegal-immigration initiative passed into law last November, requires Arizona's 2.7 million voters to show proof of identity to cast a ballot. That could mean a driver's license, a passport or some other document with a name, address and photograph. A mail ballot is far simpler. It requires only a signature. "They exempted all the people who vote by mail," Rodriguez said of the Protect Arizona Now group that was the driving force behind Prop. 200. The first local test of the new law comes on March 8 with elections in South Tucson, Marana, Sahuarita and the Metropolitan Water District. Early voting in those contests begins today. A significantly larger pool of voters is expected on May 17, when Tucson decides the fate of a $142 million water bond issue. In the last election, about 35 percent of all ballots cast in Pima County were mailed. In processing them, officials check the signature on the ballot against the voter's signature on the registration form kept by the Recorder's Office. "This is the check that county recorders already do," said Kevin Tyne, a deputy secretary of state. Tyne emphasized that because all signatures are verified, voting by mail does not amount to a loophole through which voters can bypass the provisions of Prop. 200. "They already verify each and every signature," he said. Rodriguez and Arizona's other 14 county recorders met in Phoenix on Wednesday to decide how to apply the new law. After the meeting, she said confusing questions persist about a number of issues, such as whether a driver's license is valid proof of citizenship. "My suggestion was that they take a group picture of us now and another one a year from now so we can see how much we age dealing with this thing," she joked. Rodriguez is not alone in believing that Prop. 200 could spur a surge in mail voting. "People could be really offended if they have to show ID when they never had to before," said Dan Eckstrom, a former Pima County supervisor and former mayor of South Tucson. "For the older, regular voters, the people who vote all the time, they could say, 'If I never had to this before, why should I do it now?' " An even bigger concern, Eckstrom added, is that the frustration could prompt some to not vote at all. "It's hard to say what's going to happen," he said. While Prop. 200's voting provisions were cleared by the U.S. Justice Department last month, one local human rights group remains concerned it will impose barriers to voting on people of color and the elderly, among others. Derechos Humanos is spearheading an effort to overturn the decision. "Federal voting rights laws guarantee that no person shall be denied the right to vote on account of race or color," the group wrote in an e-mail. "Prop. 200 will disenfranchise many citizens." Backers of the proposition say the goal is to prevent non-citizens from voting. The initiative also makes Arizona the first state to require proof of citizenship when registering to vote. It also makes it a crime if public employees fail to report an illegal immigrant seeking benefits. Tucson resident Alden Gates said he has no problem showing his ID when voting, so the law probably won't keep him from casting a ballot at his neighborhood polling place. "I like to see my ballot go into the collection box," he said. "If I mail it in, I'll never know for sure if it gets counted." Same for Marilyn Malone, who voted by mail last November but prefers to vote in person. "It won't change my behavior," she said. "I love going to the polls. It makes me feel American." Voting by mail has grown in popularity in recent years as voters realized its convenience. Ballots can be completed at home well before an election, without having to deal with the lines or bother of going to a polling location. This, in turn, has had an impact on campaigning as politicians running for office are forced to contend with the increasing number of voters who make up their minds well before Election Day. Mail voting also is appreciated by political parties, which candidates rely on to organize get-out-the vote efforts. "It allows us to lock up the base early," said Judi White, chairwoman of the Pima County Republican Party. "Many older voters will vote by mail, people with careers who are busy, a lot of people will be doing this," she said. In the last election, 156,293 county voters took advantage of mail voting out of 448,050 total ballots cast, Rodriguez said. Partly because of the growth in mail voting, Rodriguez supports a bill that has been introduced in the state Senate that would allow voters to be put on "permanent early ballot status." Voters now must request a mail ballot for each election in which they plan to participate. "This bill saves taxpayers money and it's a convenience for voters," she said. Some jurisdictions have decided to conduct only mail balloting. That will be the case in Sahuarita on March 8, when voters pick members of the town council. South Tucson and Marana will also vote for council members, while the Metro Water District has a bond election.