MILWAUKEE — The Milwaukee Brewers’ famous racing sausage mascots rambled about the sprawling parking lot of the Miller Park baseball stadium for a few hours on Tuesday, but they weren’t there to promote sausage or baseball: It was National Voter Registration Day.

The people in the sausage costumes had no need to don face masks, but a few dozen Milwaukee election workers were wearing them, along with high-visibility vests, as they held the city’s first drive-through voter registration event.

Wisconsin allows voters to register at the polls on Election Day, but Jessie Eisenhauer, 39, a medical researcher who needed to change her registered address, chose instead to drive to Miller Park on her way home from work.

“Normally, I would register the day of, but with this pandemic going on, I think less time spent at the voting facility is probably better,” said Ms. Eisenhauer, who wore a colorful mask depicting shelves of books and a smiling bookworm.

Despite the good cheer in the parking lot, election workers were trying to reverse a troubling trend: declining voter registration in Milwaukee in recent years. 

The number of registered voters is down by 30,000 since 2016, thanks in part to the state’s purges of inactive voters, according to Claire Woodall-Vogg, the city’s election commissioner. About 300,000 people are currently on the voter rolls.

With the coronavirus pandemic keeping many residents away from city libraries and grocery stores, which traditionally host voter registration tables, the commission added the drive-through registration option this year, and plans to allow drive-through voting, too.

“We registered 70 City of Milwaukee voters at Miller Park and helped 87 people apply for a ballot by mail,” Ms. Woodall-Vogg said of the event on Tuesday. She added that the stadium grounds also would be used for “true, drive-through voting” on Oct. 20, the first day of early in-person voting in the state.

At a voter registration table set up on Tuesday outside a Cousins sandwich shop in the Midtown neighborhood, Marian Cotton hesitated, then went to her car to fetch her ID. 

“I didn’t vote in 2016,” Ms. Cotton, a 53-year-old school bus driver from Milwaukee, admitted. “I was really not motivated.”

“There is no change in Milwaukee,” Ms. Cotton added. “We want racial equality and a peaceful way of life — an end to all this violence.” This fall, Ms. Cotton says, she will vote for Mr. Biden and will encourage family members to vote, too.

Kushan Stampley, who was helping Ms. Cotton, discovered that she had previously registered but needed to update her address. “See? That was so easy to do,” he said. “We could do it all on your phone.”

“It helps that we’re out here,” said Mr. Stampley, who works for Souls to the Polls, an alliance of Milwaukee churches that works to encourage voting. Of the eight or nine people who stopped to register that day, Mr. Stampley said, most had never voted. “They don’t feel it will make a difference,” he said.

Charmaine Clayborn, however, was eager to register for the first time, noting that, for years, she could not vote because of a felony conviction. “I served my time and I completed my probation,” she said. (In Wisconsin, ex-felons may vote if they are no longer in jail or on extended supervision.)

“I want to vote so I can make a change,” said Ms. Clayborn, 33, a manager at a different Cousins shop. “There’s too much hurt and killing in the world and Black people not getting a chance. A lot of my people don’t vote, but we’ve got to get up and vote, if we want to be heard, not just protest. I’m trying to do that.”