More voting by mail plus a return of Mitt Romney to the ballot helped increase voter turnout in this year’s primary election — but most Utahns still skipped it, officials said Monday as Lt. Gov. Spencer Cox’s office released the final canvass of results.

About “29 percent of the active voters in the state cast a vote in the [June 26] primary. In 2016, it was 24 percent. So overall it was up,” said Justin Lee, director of elections for Cox.

He noted that comparing turnout between primaries is tricky, because not all areas or parties have candidates competing in different years.

But he said one of the better measures this time comes because Republicans had a high-interest statewide primary in the last two election years — in the U.S. Senate race this year between former GOP presidential nominee Romney and Mike Kennedy, and in the governor’s race in 2016 between Gary Herbert and Jonathan Johnson.

“This year, we had 51 percent of active registered Republicans [defined as anyone who has voted or registered during the past eight years] voting in the Senate race. In 2016, we only had 38 percent of them voting in the statewide gubernatorial race,” Lee said.

That means 336,792 Republicans cast ballots in this year’s primary election, up by 90,263 from two years earlier.

“Whether that’s a Mitt Romney bump or a vote-by-mail bump or a combination, it’s hard to say,” Lee said. “But we certainly had more people voting this year than we have in the past.”

For the record, the final count shows that Romney won 71.3 percent of that vote to 28.7 percent for Kennedy, a state representative. Romney now faces Democrat Jenny Wilson, a member of the Salt Lake County Council, in the general election.

In 2016, 21 of Utah’s 29 counties conducted elections primarily by mail. This year, all except Emery and Carbon relied mostly on voting by mail.

“Vote-by-mail does seem to increase turnout, particularly in smaller-turnout elections like primary or municipal elections,” Lee said. “Anecdotally, it does seem like the best advertising that there is an election is getting a ballot in the mail.”

While most voters now receive ballots in the mail, they still have the option of casting ballots in person if they choose. But few do.

“This year, 90 percent of ballots were cast by mail. In 2016, it was about 81 percent. So we had more people voting and a higher percentage of people voting by mail,” Lee said.

Turnout usually improves dramatically in the general election, which this year is on Nov. 6 — but by-mail ballots will start arriving in mid-October.

Two years ago during the wild presidential election between Donald Trump and Hillary Clinton, more Utahns cast ballots than ever: 1.15 million people — or 82 percent of the state’s active registered voters. That was the highest turnout since 1964, when 89 percent voted.

But Utah's turnout that year looks less impressive when it is figured as a percentage of the "voting eligible population," or anyone who is old enough to vote and is legally eligible. Only 56.7 percent of such Utahns cast ballots in 2016 — meaning more than four of 10 did not bother to register.