WASHINGTON — In an election characterized by name-calling, classified emails and “small hands,” voter turnout has reached its second-highest level in the past 35 years.

Voter turnout has been double what it was in 2012, and is less than 2 percent behind the level during the 2008 presidential election, according to the Pew Research Center, a bipartisan organization.

The turnout is especially noteworthy for Republicans. Data from the United States Election Project, which compiles and analyzes election results and statistics, show Republican voting in primaries and caucuses is up across the board.

States like Idaho, Virginia and Missouri have seen increases of more than 200 percent in Republican turnout compared to 2012. Traditionally blue states have also seen spikes relative to 2012. Massachusetts and Maine, for example, had increases of 72 percent and 220 percent, respectively.

Although Democrats in many states have not flocked to voting centers in the same numbers as Republicans, their turnout in 2016 has largely outpaced levels from the last presidential election, during which just 6.3 percent voted in primaries, according to Pew.

In some cases, the high volume of voters exceeded the resources available at election sites. Democratic caucus sites in Boulder County, Colorado, had lines so long that delegates were selected before thousands of voters ever made it inside. And in Portland, Maine, officials had to move a caucus at Deering High School to the school’s parking lot to accommodate the large number of voters.

Public interest in the election appears to be the driving force behind this season’s surge in primary and caucus participation, according to Michael McDonald, an associate professor of political science at the University of Florida and the director of the Election Project, a website devoted to providing detailed information about U.S. elections.

“People vote in an election if the election is interesting, and there are two factors that are particularly relevant in this election cycle,” McDonald said. Those factors include how competitive the election is, and how different its participating candidates are from one another.

The 2016 election, for instance, has no incumbent candidate and a large number of candidates, two elements that increase competitiveness, according to Ballotpedia, a nonpartisan curator of political information. The unorthodox campaign of Republican candidate Donald Trump is another factor.

“Trump is offering a different kind of choice in terms of an anti-establishment choice,” said Jan Leighley, a professor of government at American University and a researcher of political behavior and voter turnout. “You also have a lot of other candidates on the ground trying to get their supporters to the polls. You put those two things together and, not surprisingly, you get higher turnout.”

Policy differences between the parties and within the parties also spur turnout — Planned Parenthood funding, for example. Republican voter turnout likely has been driven by the sheer number of candidates — 17 at one point — with starkly different stances on issues, from immigration to foreign policy.

“If we look at the exit polls, what we can see is that Democrats are largely satisfied with either Clinton or Sanders as their nominee, depending on the state,” McDonald said. “Now, you put that on the Republican side, and you see in the exit polls that 50 percent or less … would be satisfied with any one of the particular candidates.”

While participation levels thus far appear to favor Republicans, research suggests primary elections are poor predictors of general election turnouts. In fact, since at least 1972 more general election victories have gone to the party with the lower primary turnout.

The various methods by which states conduct primary elections or caucuses, as well as the turbulent nature of presidential elections, further complicate drawing inferences about the general election.

“The difficulty in making generalizations is that the institutions are always changing — the calendar that the parties are under is changing, the states themselves change,” said Lonna Atkeson, a professor of political science at the University of New Mexico and the director of the Center for the Study of Voting, Elections and Democracy. “Every time a party loses, they go, ‘Oh we’ve got to change things.’?”

Moreover, this year’s election is unique in that the Republican Party is so deeply divided that it may not abide by election traditions, American University’s Leighley said.

“I don’t know if individuals who, for example, supported Rubio or Kasich or Cruz, how much they’ll come back to love Trump if he ends up being the Republican candidate,” Leighley said. “That’s where voting and who you’re voting for could muck things up. This might be an unusual year in that the Republican Party is so divisive you may not see that level of bounce back.”