At Boston’s southeastern edge, along the gray Neponset River, sits one of the city’s whitest and most conservative pockets.

Dorchester’s Ward 16, Precinct 12 is home to Florian Hall, where an enormous red-tiled mural announces the home base of the firefighters union, and where on Tuesday, hundreds will show up to vote. Local 718, the firefighters union, has backed Essaibi George, the race’s underdog and its more moderate candidate. In all likelihood, these voters overwhelmingly will, too.

On the hilly streets, lined with modest single- or two-family homes bordered by chain-link fences, hot pink lawn signs backing Essaibi George are almost as common as the Halloween spiderwebs, skeletons, and blow-up figures. American flags are ubiquitous; less common, but visible, are their cousins with thin blue or thin red lines, cheering the work of police officers and firefighters.

The lawn signs tell the story: White, Irish candidates are well-represented; one sign for Wu sits lonely at the front of a yard. Donald Trump almost defeated Joe Biden here last year, in his best showing anywhere in the city.

In a changing city, here is a place that clings to its traditions, where families tend to own their homes and stay in them, and where the demographics change little over time. It remains the Irish-American enclave many imagine Boston to be, even as much of the city has shed that identity. Many residents are government workers and first responders, police officers or firefighters or city staff who keep up with Boston politics in part because of its impact on their lives.

“In Dorchester in general, politics is sport, and mayoral elections are our Super Bowl,” said state Representative Dan Hunt, who chairs the Ward 16 Democratic Committee that includes the area. “So people are involved. People are informed.”

It’s “a neighborhood-oriented neighborhood” — the kind of place where folks genuinely care about each other, where they shop locally and are quick to recommend each other’s businesses, said Nancy Flynn, who owns Dorchester Door and Window, which has been a neighbor to Florian Hall for more than three decades.

They come together on Election Days, too. It’s consistently one of the highest-turnout precincts in the city. In September, it saw the highest participation of any precinct in Boston, at 62 percent — more than double the city average. And residents often vote cohesively. Essaibi George won four of every five votes cast in this precinct during the preliminary, her strongest showing anywhere in the city — and the best showing of any candidate in any precinct in the city.

“Our membership tends to be very civically engaged,” said Steve Bickerton, president of the Cedar Grove Civic Association, which includes a number of Dorchester precincts.

One key to that voting pattern: The Keystone Apartments, a hulking brick building home to hundreds of seniors and disabled residents. From its sprawling parking lot, it’s an easy five-minute walk up Hallet Street (or a shorter ride, often offered by campaign staff) to Florian Hall — and on the first Tuesday in November, it feels, Hunt said, more like a social gathering than an errand or obligation.

The political machine that defined old Boston politics is well rooted in East Boston. For decades, candidates have converged here for Election Day parties at Santarpio’s on Chelsea Street, a tradition involving pizza and political bravado.

Joia Santarpio, who runs the restaurant now, recalls how the city’s would-be bosses — mostly men — would arrive in suits. Now, though, the candidates are more diverse — people of color and women — and they bring their whole staff. These more recent gatherings feel more like celebrations than displays of political might.

“It just seems more inclusive,” said Santarpio, who doesn’t mind your politics, as long as you like pizza.

As Boston’s political landscape shifts, so too has East Boston, a neighborhood that has long been defined by Boston’s Italian-American community. Newer, younger professionals are buying lofty condos. Immigrants still settle here, but these days they are Arab-speaking newcomers or those from Latin American communities.

For the better part of the last 40 years, the neighborhood has been represented by a white male of Italian-American descent. Now, Councilor Lydia Edwards, a Black woman who was not born in Boston, represents the area after beating out a white male opponent backed by then-mayor Martin J. Walsh in the 2017 election.

Walsh narrowly won the neighborhood in 2013, by just 66 votes. But in the preliminary election, Wu dominated East Boston, with 37 percent of the vote to 28 percent for Essaibi George, the runner-up here.

Brian Gannon, a business analyst who moved there 12 years ago and has helped organize a ward committee of progressive activists, said he first saw the galvanization of the community take hold in 2013, when residents killed the proposed casino at Suffolk Downs — even though the political establishment wanted it.

“There was a realization that you were underrepresented,” he said, because the establishment failed to recognize the wishes of the community. He said it was time “to change things up from the old guard.”

Last week, Eileen Moran dropped her vote off at the early ballot box at the East Boston library branch. A retired hospital chaplain, she is fairly new to the neighborhood — she and her husband moved in the spring from Essaibi George territory in Dorchester — but she has already seen the activism in the community, particularly over concerns with rising flood waters. She shares those concerns.

Moran said she would be fine with either candidate. But she voted for Wu.

“I think she [Essaibi George] is still the old school, I just think let’s give Wu a chance with some of her ideas,” Moran said.

In this particular pub, in this particular neighborhood, Boston’s well-worn provincialism is alive and well.

Some voters might balk at admitting they care where a mayoral candidate was born and raised. Not the boomer-aged white men who gathered one recent afternoon at Corrib Pub Restaurant, a decades-old Brighton Center staple. Huge developments have transformed swaths of the neighborhood outside — a familiar tale in Boston — but inside, a stubborn slice of old Boston remains.

A man at the corner of the bar doing a crossword and nursing a Coors Light said he likes that Essaibi George grew up in the city, and the fact that Wu did not is a strike against her in his eyes. He declined to be named.

“I’m going with the Dorchester girl,” he said.

Another patron said Wu is “too far left for me.” The man seated across from him said he likes Essaibi George because she “gets along with the cops.”

Jutting out on the city’s western edge, this neighborhood is more politically complex than you’d imagine listening to those holding forth here over burgers and beer. If September’s preliminary results are any indication, they are in the minority in Allston-Brighton nowadays; Wu won every precinct here, which is home to about 77,000 residents and is geographically isolated from the rest of the city, flanked by the Charles River to the north, Brookline to the south, and Newton to the west.

The neighborhood was once a bastion of traditionalist power in politics. This is Bill Galvin territory. It’s the City Council district Mark Ciommo represented for more than a decade. Ciommo was known as someone who leaned relatively conservative, at least for some city political circles, and leveraged his tenure as the head of a Brighton senior center to ballot box success.

Now, Liz Breadon, an immigrant from Northern Ireland who is the first openly gay woman to serve on the council, represents this part of the city, known for housing hordes of college students and young professionals. Breadon agrees with the sentiment that the district is in some ways more progressive than it was during Ciommo’s tenure, while adding that she thinks the neighborhood has had a progressive streak for some time.

It also boasts a very young populace. A higher percentage of 20- to 34-year-olds (67 percent) live in Allston than in any other Boston neighborhood, according to city data. In Brighton, that cohort makes up 52 percent of the population. The vast majority of residents in both Brighton and Allston are renters, leaving the neighborhood in a constant state of flux.

A short walk away from the Corrib, Wu support flourishes inside Matt’s Barber Shop.

Electric clipper in hand, shop owner Matt Charette, a 37-year-old who grew up on Cape Cod but moved to Brighton in 2003, said Wu seemed “pretty likable, politics aside.”

“Hopefully she’ll have a better plan for development in the city moving forward,” he said. “Under [former mayor Martin] Walsh, it was just open season for big money developers in the city.”

Another barber, 31-year-old Mackenzie Murray, supports Wu’s housing policies, including the fact that she is open to rent controls. She likes that Wu doesn’t seem interested in “giving cops more money.”

Growing up in the 1970s, Fatima Ali-Salaam recalled, hers was the only Panamanian family on her street in Mattapan, a crucial part of the voter-rich territory of Ward 18.

“Now we have a lot more people from [Central America and] the Caribbean than before,” said Ali-Salaam, the head of Greater Mattapan Neighborhood Council. “That was not the case in the 1970s.”

Ward 18, a broad swath that includes Hyde Park and large sections of Mattapan and Roslindale was once the home of the late mayor Thomas M. Menino, the city’s first Italian-American mayor. Its residents held down jobs in hospitals, schools, and local government.

Now, people of color make up about 75 percent of the population in Ward 18′s neighborhoods. Many are immigrants from Haiti, Jamaica, Trinidad and Tobago, and the Dominican Republic. They, too, work in schools, hospitals, and local government.

“It was a working-class, blue-collar [ward],” said City Councilor Ricardo Arroyo, who grew up in Hyde Park and represents District 5, which includes most of Ward 18.

“It went from working-class, blue-collar, white workers to working-class, blue-collar, Black and Latino workers and city workers. It’s a very diverse [ward] now in a way that it wasn’t before.”

Here bakeries serve Haitian pastries, and Creole voices spill from the church pews.

Turnout, no matter the election year, is always high.

Arroyo, who has publicly endorsed Wu over Essaibi George, said the best and only way to succeed here as a candidate is to address working-class issues and racial equity issues — such as better access to homeownership for the children of the families that have roots here.

Few places capture Boston’s promise — or problems — quite like Chinatown.

The neighborhood, which stretches from downtown and Boston Common to the Southeast Expressway and Massachusetts Turnpike, is one of the city’s most diverse, rooted in the working-class immigrant families that settled here. Their mom-and-pop shops still line many streets, in increasingly stark contrast to the ritzy skyscrapers and development projects that have sprouted up around it.

Yet Chinatown has been especially vulnerable to issues that have bedeviled Boston as a whole: the soaring cost of housing pushing out many longtime residents and environmental pollution and congestion, to say nothing of the pandemic’s blow to the small businesses that call the area home.

“We’re on the front lines,” said Suzanne Lee, president emeritus of the Chinese Progressive Association. “We’ve been here over a hundred years, and the way we are still fighting for the survival of Chinatown illustrates how the establishment sees us.”

This year’s mayoral election — more than ever — will test the political clout here that advocates say they have been building over decades. More politicians now court Chinatown’s voter-rich precinct than in years prior, said Angie Liou, executive director of the Asian Community Development Corporation, which helped host bilingual town halls this year.

Both Wu and Essaibi George have campaigned here often. Last month Wu rallied here alongside Senator Elizabeth Warren, while Essaibi George stopped by a food share program to win over voters firsthand.

Much of the neighborhood — which is dominated by Ward 3′s Precinct 8 — has leaned progressive. It backed John Connolly over Martin J. Walsh in 2013. Wu won the precinct handily in September’s preliminary election with 50 percent of the vote.

But Essaibi George’s campaign in recent weeks has sought to narrow the gap, particularly with those who went for other candidates such as Acting Mayor Kim Janey or John Barros. On one recent Saturday, a volunteer passed out leaflets supporting Essaibi George outside the popular C-Mart Supermarket just south of Herald Street.

And though the precinct is expected to favor Wu, a Taiwanese American, activists have stressed Chinatown is made of many communities and is hardly a monolith. Only 38.5 percent of the precinct is Asian — 44 percent is white, while Black and Latino voters make up 5.2 and 7.8 percent respectively.

“Chinatown is a symbolic community,” said Betty Lim King, a leader of the AAPI Action Group which endorsed Essaibi George earlier this fall. “We do want an Asian American representative, but Michelle Wu is not the right one.”

Wu, she said, has not shown up enough in the precinct, and King pointed to what she said was Essaibi George’s more appealing stance on public safety and her record as a former teacher. Essaibi George “is reasonable. Her goals are realistic,” she added.

The Holy Name Rotary in West Roxbury has long been hallowed political ground for candidates, who flock here for high-visibility standouts on voter-rich turf. The wide traffic circle borders a Catholic parish hall that serves as the polling place for four precincts of Ward 20, which reliably delivers the highest turnout in the city.

Indeed, Ward 20 singlehandedly produced 12 percent of the city’s vote tally in the Sept. 14 preliminary election.

The following day, the Holy Name rotary was the backdrop for another high-stakes showdown — a “Back the Blue” rally where activists who turned out to show their support for police faced counterprotesters from Black Lives Matter for the second year in a row.

The dueling demonstrations showcased the strength of clashing passions in a neighborhood that’s home to an uncommon concentration of police officers and civil servants — but that is also attracting newcomers with a more progressive worldview.

Those differences became ever more pitched with the polarization of national politics of recent years. The Trump-supporting Ward 20 Republican Committee even invited Steve Bannon for a talk early last year.

Given its more moderate tilt and its high concentration of police who make their homes here, it makes sense that Ward 20 would favor Essaibi George, the candidate who has embraced the support by police, blasted her opponent for proposing to shift funding away from the force, and been endorsed by the former police commissioner, as well as the city’s firefighters union and paramedics union. Essaibi George may be from Dorchester, but these are clearly her people, and Ward 20 backed her over Wu 40 percent to 34 percent in September.

“I feel very confident about our position in Ward 20 in West Roxbury,” said her campaign manager, Cameron Charbonnier.

But Wu’s team is not ceding any ground, noting that the preliminary included three other candidates who amassed a collective 2,200 votes in the precincts of Ward 20 that lie in West Roxbury — more than the margin of her loss to Essaibi George here. Wu has consistently beaten Essaibi George in Ward 20 for at-large council races over the past four election cycles.

That makes this hotly contested territory, with political leanings less clear-cut than its reputation might suggest. Ward 20, whiter than any Boston neighborhood save South Boston and Back Bay, might be caricatured as a civil service haven for long-term residents, but it is dotted with new arrivals.

“It’s becoming more diverse. More people from away are moving in,” said progressive activist Gretchen Dietz, outside one of the polling places on the first day of early voting. “There are two West Roxburys.”