JULIA MEJIA WASN’T “virtue signaling” or making any other big statement as she stepped on a Red Line car Wednesday morning at Ashmont Station. As is the case for thousands of other daily MBTA riders, it’s simply how the Dorchester single mother gets into town. 

But Mejia was anything but another face in the crowd as the train rumbled toward Park Street. On Monday night, she was declared the winner of the fourth and final at-large seat on the Boston City Council by a single vote, and people have definitely taken note.

“Hey, Miss Feisty!” called out a woman seated across from Mejia.  

“Congratulations. I voted for you,” said a man who boarded a couple of stops later. 

It’s been a whirlwind ride of sudden star power for Mejia, a first-time candidate up against a slew of better-funded rivals, who on election night appeared to have eked out a 10-vote win over Alejandra St. Guillen. When a citywide recount was completed this week, that margin was reduced to just one vote. 

As thrilled as she is to be preparing to take office in January, Mejia said during an impromptu 20-minute interview as the train made its way downtown from Dorchester, she would have regarded it as a win no matter how the recount turned out. 

“We set out initially to build political power, to create an opportunity for people who have never been engaged to really recognize the importance of the electoral process and the role that they play. So the fact that we were able to do that was, in and of itself, a win,” she said. “There were people who had never registered to vote, who have never been engaged, that had something to believe in. So it feels incredible. But I had peace in my heart either way.” 

Many pointed out that a progressive Latina was poised to win a seat regardless of the outcome of the recount. While it was inevitable that one side would end up very disappointed, what’s remarkable is that Mejia seems to share in that painful sense of coming so close but falling short. 

“I had survivor’s guilt to be honest with you,” she said, tearing up. “I felt really bad about the fact that Alejandra did not win. I really wanted us to both win.” 

When a supporter let out a huge cheer as the final result was announced at City Hall on Monday, Mejia said she quickly tamped down the celebration. “I said, no, cut it out,” she said. “Because I looked over and saw Alejandra’s supporters, and I said, we’re not celebrating that way knowing what was happening on their side.“ 

The founder of a nonprofit that helps parents advocate on education issues affecting their children, Mejia called her win a victory for grass-roots activism and everyday Bostonians. “I was a first-time candidate, no name recognition, less money than everybody else,” she said. “It’s a big win for single moms and regular folks like us to be able to say, look, if I can do this, you can too.” 

She said the one-vote victory “played into the narrative” she campaigned on in communities that often feel voiceless — that everyone’s vote counts.

It also produced a sense of deja vu for the 50-year-old Dorchester resident. In 2000, Mejia was working as a producer for MTV, traveling the country as part of the network’s effort to encourage young people to vote in the presidential contest between Al Gore and George Bush that wound up being decided by the Supreme Court. 

Nearly two decades later, her own campaign for office could have ended up in court, too, but St. Guillen announced on Tuesday that she wouldn’t take that step and conceded the race. 

A native of the Dominican Republic who arrived in the US at age 5 not speaking English, Mejia became the first person in her family to finish high school as well as get a college degree. She was raised by a single parent — a one-time undocumented immigrant who now has US citizenship and was able to cast a vote last month for her daughter. While growing up Mejia would head into town after school to the John Hancock Tower to help her mother, who spent nights cleaning offices there after working a day shift in an area factory. 

“To go from cleaning offices with my mom to being a city councilor — it’s a big deal,” she said. “It goes to show that the American Dream is possible.”

Mejia credits her years of work on behalf of young people and parents to a single moment at Dorchester High School, where she had returned after having dropped out.  She was a 19-and-half-year-old student there when popular Boston television news anchor Liz Walker delivered an uplifting talk at the school. “Her story inspired me to graduate high school and go to college,” said Mejia. “I would not be here today if it was not for her.” 

Mejia exudes warmth and has an open, down-to-earth bearing, traits that seem likely to make her a candid voice on the council. 

“I’m very feisty,” she said — speaking before the woman on the train had called out to her with the same appellation. “I speak my mind. I wear my heart on my sleeve. I don’t have a poker face. I came in as an independent voice and I’m going to change the way we do business. I think we can make things easier for folks to have a voice at the table.”

One of the most direct ways she hopes to do that is by pushing the council to move its weekly meetings from the middle of a weekday to an evening so that more members of the public can attend. She also favors a return to an elected school committee. 

She backs rent control to deal with soaring housing costs, though she would support measures to help small landlords, perhaps through some type of tax breaks. And Mejia says she wants to require 50 percent affordable housing units in any new development, though she acknowledges that’s more of an initial bargaining position than likely final figure.

Mejia is a former organizer with the Massachusetts Charter Public School Association, but she has shed her fervent backing for the independently run, but publicly funded, schools for a more balanced stand.

“I’m a critical friend,” she said of her attitude toward charters. “I believe they’re not the end all and be all” but “they do have a role.” She said charter schools’ autonomy sometimes infringes on parents’ involvement, and she’d like to see charters play a bigger part in school innovation.

“They’re supposed to be labs of innovation,” she said. “They’re not here to compete with the district. I want to see them be more of a partner.” 

If there’s an overarching theme to how she’s thinking about her new role, it’s rooted in Mejia’s years of work with others like her, who have been largely cut off from the centers of political power in Boston and the riches of its booming economy. 

“It’s a city of haves and have-nots. I’ve always been on the have-not side,” said Mejia, who was on her way to City Hall to take in the last City Council meeting of the year as an observer before taking office next month. “There are a lot of people who are fed up. We’re tired. I don’t want any more lip service. I want to go in there and make some things happen.”