MINNEAPOLIS — Excitement over wide-open Republican and Democratic presidential primaries brought 320,000 Minnesotans, or about 8 percent of eligible voters, out to pick presidential candidates on a cold March night in 2016.

Such a showing would be abysmally low for a presidential election in Minnesota, when voter turnout routinely tops 70 percent. But it’s a really big showing for a caucus. So big that it overwhelmed some of the state’s precinct locations with hour-long lines, and, in some cases, not enough ballots.

Two months later, then-Gov. Mark Dayton signed a bipartisan bill that changed the way the state chooses who its presidential delegates go to, switching from the party-run caucus system to a state-administered primary election. (Party caucuses aren’t going anywhere — they’re just not how Minnesota chooses presidential candidates anymore.)Minnesota’s not alone. States are increasingly souring on the caucus system as a means of awarding presidential delegates to pick a party nominee.

Experts say the switch could change not only who participates in presidential selections, but also the way candidates campaign and maybe even which candidates are chosen.

Minnesotans have registered their presidential preferences in precinct caucuses for most of the last century.

As opposed to a primary, where voters go to their polling place and cast a ballot, caucuses are like big neighborhood meetings. In addition to picking candidates, caucuses are held to discuss party business. They start at a given time — usually 7 p.m. on a Tuesday, and end an hour or two later.

Fans of caucuses say the discussion component makes them a higher quality system, said Costas Panagopoulos, a professor of political science at Northeastern University who studies voting behavior. “The deliberative nature of these caucuses, and the more direct interaction with voters and neighborhoods, et cetera, is something that is perceived by many to be an advantage and a much higher-quality process,” he said.

Detractors say the fact you have to be there at a specific time to make your preference known limits who shows up.

Caucuses are deeply rooted in American political tradition, beginning as meetings where party elites would decide party business and choose candidates. Over time, the process opened up to a wider swath of participants. Seeking to further open up the process, lots of states started switching to the primary process in the ‘70s.

Minnesota has flirted with both systems, switching from caucuses to presidential primaries, and then back again, every three to four decades since the nineteen-teens, according to a history of Minnesota primaries by Eric Ostermeier, a research fellow at the Humphrey School of Public Affairs.

Primary turnout is always significantly lower than general election turnout in the same election cycle. But if primary turnout is low, caucus turnout is lower.

Amid the 2016 election, Sabato’s Crystal Ball, a political predictions website, found that turnout was more than three times higher in states that had held primaries, as of late April, than in states that had held caucuses.

The nonprofit news outlet MinnPost provided this article to The Associated Press through a collaboration with Institute for Nonprofit News.