Read all of our coverage on 2016 ballot measures at governing.com/ballotmeasures.

Suppose every adult was automatically registered to vote. How many more people would actually cast ballots? Some states will soon find out.

Since Oregon became the first to create an automatic voter registration system last year, California, Connecticut, Vermont and West Virginia have all followed suit.

Alaska has just joined the list. Alaska residents on Tuesday approved a ballot measure to allow voters to be registered automatically by the state. It is the first state where voters themselves created such a system.

Automatically registering people is intended to help more citizens vote. Oregon, for example, has already seen its voter rolls swell by some 250,000. None of the other states, though, had their systems completely up and running in time for the election.

Still, the question remains: How many of the people who have been signed up almost by remote control will actually turn out to vote?

"The expectations that now everyone will vote, or that there will be a huge increase in voting, are unlikely," said Jan Leighley, a voting expert at American University. "There's not going to be a magic switch that turns over everyone to voting."

The idea of registering voters automatically has quickly gained currency, with 29 states considering proposals this year. So far, however, only Democratic governors have signed automatic voter registration bills. Republican Govs. Chris Christie of New Jersey and Bruce Rauner of Illinois each vetoed automatic voter registration bills this year.

In states that have passed automatic voter registration, their primary tool is the Department of Motor Vehicles. When a citizen gets a new license or renews an old one, his or her information is automatically entered or updated on the voter rolls -- unless he or she decides to opt out.

In Alaska, the main database will be the state's Permanent Fund, which distributes oil royalty money to residents. More Alaskans apply for the Permanent Fund than a driver's license, particularly in rural communities, said Kit Reitmeier, co-chair of the initiative's campaign.

The measure took more than 60 percent of the vote. It was backed by a wide range of supporters -- from the Alaska branch of the American Civil Liberties Union to the oil company BP, one of the state's most powerful interests. Although originally pushed by Democrats, the measure was endorsed by both of the state's Republican U.S. senators.

By contrast, there was no organized opposition. In fact, the state couldn't even find anyone to write an argument against the measure for the official voter guide.

So, thousands more adults in Alaska will soon be registered to vote. But how many of them will turn out in subsequent elections?

When states allow Election Day registration, said the voting expert Leighley, it increases turnout by 3 to 6 percentage points. That's not nothing, but it's not a huge uptick in a country where more than half the people choose not to vote. And, she said, same-day registration is actually more conducive to encouraging voting than automatic voter registration.

"With Election Day registration, they can register and typically cast a ballot at the same place," said Leighley. "That's a two-for-one stop."

But with automatic voter registration, people haven't necessarily expressed any interest in voting.

Still, registration can be a serious barrier. Many people do not realize they might have to register weeks before an election, or that they need to update their information when they move. Making registration automatic makes it the state's responsibility to ensure that people who are eligible to vote are signed up to do so.

The Alaska measure had some $1 million behind it, including six-figure contributions from the New Venture Fund, a Washington-based foundation, and the Alaska chapter of the National Education Association.

Despite the lack of organized opposition, the measure did have some critics.

Opponents called it a transparent effort by Democratic interest groups to stack the registration lists with their supporters. The few voices speaking out against the measure also raised concerns about voter fraud, although supporters of automatic voter registration in Alaska, as in other states, insist that there are safeguards to ensure that only citizens are registered.

Automatic voter registration may not lead to a huge influx of new voters, but it will certainly create the opportunity for thousands of additional citizens.

Read all of our coverage on 2016 ballot measures at governing.com/ballotmeasures.

*This story has been updated to clarify that only Oregon has its automatic voter registration system fully implemented.