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SALEM, Ore. — Election officials across the U.S. are worrying about whether their aging voting machines will fail next Tuesday, whether hackers will try to create chaos and whether voters will even show up to vote.

In Oregon, they don't have to worry as much, because they don't have any voting machines — or any polling places.

Twenty years ago, Oregon became the first state in the nation to conduct all statewide elections entirely by mail. Three weeks before each election, all of Oregon's nearly 2.7 million registered voters are sent a ballot by the U.S. Postal Service. Then they mark and sign their ballots and send them in.

You don't have to ask for the ballot, it just arrives. There are no forms to fill out, no voter i.d., no technology except paper and stamps. If you don't want to pay for a stamp, you can drop your ballot in a box at one of the state's hundreds of collection sites.

It's a system that consistently produces some of the highest voter participation rates in the country. In 2016, 68 percent of the state's registered voters voted, eight percent above the national average. The Oregon way is also endorsed across party lines. Current Secretary of State Dennis Richardson, a Republican, and one of his predecessors, Phil Keisling, a Democrat, agree that it gets people to vote and is cheaper and more secure than machines and polling places.

"You can't hack paper," said Richardson.

"Isn't that amazing in its simplicity?" said Keisling. "Give everyone their ballot and then let them decide where they want to mark it, whether they want to mark it at all."

Filled-out Oregon paper ballots being sorted by election workers. NBC News

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Keisling, who pushed for voting by mail as secretary of state in the 1990s, says that in-person voting can actually discourage people from voting, especially now that 32 states have some kind of voter i.d. requirement.

"I think polling places have become the single biggest voter suppression device in American politics," said Keisling.

Richardson said the Oregon way removes the "pressure of being in a voting booth."

Washington and Colorado also have mail-only elections, according to the National Conference of State Legislatures. Twenty-two states promote some elections as "all-mail," but they don't preclude in-person voting, the conference says.

Oregonians instituted vote-by-mail in a 1998 ballot measure that passed by more than two-to-one, and since then opinion polls have consistently shown overwhelming public support for the system from all voters, regardless of party.

Current Oregon Secretary of State Dennis Richardson, a Republican, and one of his predecessors, Phil Keisling, a Democrat. NBC News

Young people, the demographic of registered voters least likely to show up on Election Day, apparently like vote by mail as well. In the 2014 election, says Keisling, records showed that 45 percent of registered voters 34 and under marked a ballot — twice the level of many other states.

But what about security? You can't hack paper, but you can steal ballots. Couldn't someone swipe a ballot from a neighbor's mailbox, or from someone who has moved or died?

Keisling acknowledges this could happen, but says it would be "one of the stupidest ways to try to steal an election."

"They'd be committing a felony, vote by vote."

"A clerk once asked me to think about this," recalled Keisling, "He said, 'Phil, have you wondered why crooks don't counterfeit pennies? They go for the twenties and the hundreds if they're going to risk the jail time."

'Throw them on the scrap pile'

In order to make sure voter rolls are up to date, Oregon election officials rigorously comb death notices, change of address forms, even track social security records.

Ballots can be returned by mail, but the majority of marked ballots are returned via the state's hundreds of secure drop sites. According to election officials, younger voters say they don't like to use the post office.

Once they've been collected and brought to one of 36 county election offices around the state, all ballots are checked for authenticity. Each signature is verified against voter registration cards. The authenticated ballots then go to the vote tallying room to be counted.

As a final security feature, a voter can ask for a text confirming that his or her ballot was counted.

The tally from each county election office is sent to the secretary of state's office in the state capital of Salem.

Keisling says other states now dealing with aging voting technology should not replace those machines, but "throw them on the scrap pile."

"Go back to paper ballots," he said. "Then think hard … You ought to be looking at abolishing the polling place and moving to a system that puts the voter first."