Minnesotans — many wearing face masks — spaced apart at the polls Tuesday to cast ballots in primary elections for the U.S. Senate, Congress and an array of state legislative and local offices.

But with a historic crush of absentee ballots cast by mail before Election Day, a dramatic dip in in-person participation was noted statewide. Those who did show up did so out of habit, a perception that the state was doing well enough to mitigate COVID-19's spread or, in some cases, a belief that mail-in balloting was susceptible to fraud.

As the polls opened in the state's first election since the start of the COVID-19 pandemic, more than 500,000 people had already cast ballots by mail, surpassing the entire turnout of nearly 295,000 voters in the 2016 primary election. Altogether, about 645,000 absentee ballots had been requested by Election Day.

Minnesota managed to stave off the long lines and dysfunction experienced in other post-COVID elections this year in states such as Wisconsin and Georgia. Secretary of State Steve Simon credited counties' success in recruiting and retaining election judges in addition to the increased mail voting.

"That makes a huge difference in terms of lines, in terms of voter satisfaction, in terms of being able to handle a normal voting day," Simon said.

Up to a quarter of all absentee ballots requested had not yet arrived and could still be returned, according to the Secretary of State's Office. Simon urged patience as election workers tallied absentee ballots cast this year. Under a recent court ruling, ballots postmarked by Election Day will be accepted until Thursday. Still, Simon predicted that a "large majority of outcomes" could be known in most primary contests. All but five counties — Clearwater, Cottonwood, Lake of the Woods, Pine and Wilkin — planned to report the results that they had on election night, including incomplete results for absentee ballots.

"We'll know who won, we just won't know 100 percent the vote tally," Simon said.

Throughout the day, Simon's office monitored a makeshift "chat room" where all of the state's county and local election administrators reported "real-time issues, complaints and challenges." Few incidents or cases where voters refused to follow mask mandates, which have been challenged in court, were noted.

One voter in Bloomington refused to wear a mask, according to Julie Angeles, a head election judge. The precinct worked out a curbside voting arrangement, she said, adding that election judges have been instructed to report the voter's name on an incident log in such cases.

The scaled back in-person turnout plus plexiglass barriers, hand sanitizer stations and face masks created a scene like no other in Minnesota elections history.

Some election judges, like Bob Procaccini in Burnsville's Fifth Precinct, estimated that about a third of the usual primary turnout appeared in person. At Lakeville's Third Precinct, four lonely election judges sat in the cavernous gymnasium of Lakeville South High School, passing time by reading and snacking.

Yet in Minneapolis, where U.S. Rep. Ilhan Omar, D-Minn., soundly defeated primary challenger Antone Melton-Meaux, Minneapolis' Brian Coyle Community Center, in the heart of a Somali-rich neighborhood, produced one of the state's most active in-person voting atmospheres. In Robbinsdale, also in Omar's district and a city with a mayoral race on the ballot, some 300 people voted in person at Redeemer Evangelical Lutheran Church by early evening.

Adam Zeece, 30, was out early to vote in Minneapolis' Whittier neighborhood, not far from where George Floyd was killed by Minneapolis police earlier this summer.

"I just want to do my part in what I think would be good changes for areas like this," he said.

Gayle and Ted Procko, 76-year-old retirees in Anoka, wore masks into and out of their polling location, and used hand sanitizer as well. They said they weren't worried about getting the coronavirus from voting in person, even though she is a breast cancer survivor and he had quadruple bypass surgery this year. But they feared that voting by mail would open up the possibility of voter fraud.

"If you've got massive vote by mail, I think you've got major problems," he said. "And you might not know the next day who the president is. It might take a week. Some say it might even be beyond that. Then what?"

Simon has called Tuesday's election a "dress rehearsal" for November's general election, which is expected to greatly surpass the primary's number of absentee ballots requested. The election will also be taking place amid new reports that foreign actors such as Russia, China and Iran again seek to interfere and at a time of heightened social unrest that the Prockos compared to 1968.

"We've been married 53 years and never been through anything like this," Procko said.

Staff writers Rochelle Olson, John Reinan, Reid Forgrave and Matt McKinney contributed to this report.