After a lengthy, bitter primary constrained by the coronavirus and a contentious general-Election campaign, New Yorkers went to the polls on Tuesday to pick a mayor to lead the nation’s largest city out of the throes of the pandemic and into a new political era.

After eight years under Mayor Bill de Blasio, voters are choosing between two candidates with sharply distinct visions: Eric Adams, the Democratic nominee and a former police officer who is currently Brooklyn’s borough president; and Curtis Sliwa, the Republican founder of the Guardian Angels, who has never held public office.

Mr. Adams, who has run a campaign tightly focused on public safety, is heavily favored in a city where Democrats vastly outnumber Republicans.

Many voters across the city said that his perspective on safety and crime — he has links to police officers but has said repeatedly that he pressed for reforms from within the system — had won him their support.

Carmen Nunez, 69, of Ozone Park, Queens, said she believed that Mr. Adams was the best candidate to address safety concerns. Others said he appeared to have a strong understanding of the pulse of the city.

“The way that he spoke, he seemed to represent a lot of New Yorkers,” said Julia Yarwood, a 35-year-old Bronx resident who said she was a Democrat.

If he wins, Mr. Adams will be the city’s second Black mayor. He has promised to lead New York in a more equitable direction, pointing to his working-class roots to suggest he would be an advocate for issues of concern to less affluent New Yorkers.

Still, in contrast to the message of economic populism Mr. de Blasio rode to victory in 2013 and 2017 (he is prevented by term limits from running again), Mr. Adams has made explicit overtures to big-business leaders, arguing that they too have a significant role to play in the city’s recovery.

After voting in Bedford-Stuyvesant, Brooklyn, on Tuesday, Mr. Adams wiped away tears.

“Because I’m standing here, everyday New Yorkers are going to realize they deserve the right to stand in this city also,” he said. “This is for the little guy.”

Mr. Sliwa has also been keenly focused on public safety and addressing homelessness, but on other matters and certainly in personality, he and Mr. Adams have significant differences.

And Mr. Sliwa’s campaign has been marked by antics and eccentricities that often drew more attention than his policy positions. His trip to the polls on Tuesday grew into a fracas when he tried to bring one of his many cats with him to vote, then fought with election officials who asked him to remove his red campaign jacket when they deemed it was a violation of electioneering rules.

Mr. Sliwa, a longtime talk radio host, has long cut a large figure in New York, with some remembering him fondly from his reputation as a crime fighter during the early days of the Guardian Angels. During his campaign, he has sought to draw a contrast with Mr. Adams, whom he has called elitist.

“He’s from the streets, he knows the reality of what is going on,” said Nancy Aldrich, 59, a Queens resident who said she was a Republican. “He doesn’t blow smoke in your eyes.”

Mr. Sliwa has highlighted still-simmering questions around Mr. Adams’s residency and his financial dealings. He has also tried to capitalize on anger in some corners of the city around vaccine mandates.

That dynamic, coupled with the possibility of low voter turnout, has injected a measure of uncertainty into the final hours of the race.

Other key races have offered more drama, including several City Council elections where Republicans are fighting to hold, if not grow, their three seats in the 51-member body.

Across the state, a hotly contested rematch in the Buffalo mayor’s race and fights for district attorney on Long Island also illustrate nationwide struggles over public safety and criminal justice reform. Taken together, the results on Tuesday may offer a snapshot of the tensions over the direction and identity of the Democratic Party in New York.

Julianne McShane and James Thomas contributed reporting.

As New Yorkers cast their ballots on Tuesday, a broad range of issues, from public safety to education, were top of mind. But some said what was most significant about the current moment was its potential to usher in history.

New York has had 109 mayors; Eric Adams, the Democratic nominee, would be only the second Black man to take the city’s helm if he wins.

To Djene Keita, 30, who is Black, voting for Mr. Adams felt like casting a vote for her young son’s future. “Just having someone for him to look up to and be inspired by would be great,” said Ms. Keita, who is from Harlem.

Mark Godfrey, 65, said Mr. Adams’s ascendance felt similarly personal, a sign of “subtle changes that are occurring in the U.S.” in racial equity and representation.

Mr. Godfrey, a resident of Ozone Park in Queens who said he was an independent, said Mr. Adams’s identity as a Black man and his experiences as a police officer and a victim of police brutality meant that he “understands what being profiled is like.”

Mr. Godfrey said he hoped those experiences would give Mr. Adams a unique and valuable perspective if he takes office.

David N. Dinkins, the city’s first Black mayor, was elected to a single term in 1989 and died in 2020. He has been remembered as a mentor who inspired other Black leaders to run for office.

Some voters like Esmirna Flores, 38, recalled watching Mr. Dinkins as mayor as they cast their ballots on Tuesday. The chance to elect a second Black mayor was “absolutely awesome,” said Ms. Flores, who is Latina and lives in the Kingsbridge area of the Bronx.

“It’s about time that we have more Black representatives, more brown people representing,” she said.

Still, others like Mable Ivory, 45, a Black voter in Harlem, said they saw Mr. Adams’s history-making potential as something positive, but noted that it did not play a significant role in shaping their vote or compelling them to head to the polls.

There were also mixed feelings among some voters, who appreciated the possible landmark, but disagreed with aspects of Mr. Adams’s platform.

Gabriel Knott, 27, called the milestone an “important step forward.” But he said he remained unsure whether Mr. Adams was the best option for the job among the many Democrats he beat in June’s primary.

“It’s really key to kind of consider what is he going to do for those communities in New York City,” said Mr. Knott, who is from the Greenpoint neighborhood of Brooklyn. “But I think that it’s really still significant.”

The tension between left-wing Democrats in New York and those who consider themselves more moderate, a rift that has characterized the state’s politics for years and was a major battle in the mayoral primary in June, remained evident on Tuesday morning.

In left-leaning New York City, Eric Adams, the Democratic candidate, remains heavily favored to win Tuesday’s election. After winning the primary, he declared himself the new face of the Democratic Party, suggesting his platform and profile would be a model for other politicians across the country.

But his positions received mixed reviews from voters in the city on Election Day, with some embracing him enthusiastically and other Democrats admitting they were hesitant about casting their votes.

Allister Klingensmith, 40, expressed some ambivalence about voting for Mr. Adams because he did not see most of his political views reflected in the candidate’s platform.

“I’d like to see more done with the environment, especially environmental causes,” Mr. Klingensmith, a Democrat, said. “I just don’t think he’s doing enough there.”

On the Upper West Side of Manhattan, Edward Horton, 66, said he supported Mr. Adams in the primary election, largely because he thought the candidate would be able to increase affordable housing and tackle the city’s homeless crisis.

Mr. Horton, who is Black, also added that it would be a “good thing” to potentially see the city’s second Black mayor.

“He’s a good guy, he’s respectful and he gets along with everybody,” Mr. Horton said.

Steve Rush, 65, a retired city worker who identified himself as a moderate Democrat, said he believed that Mr. Adams could handle issues of police reform with sensitivity — he was a police officer for more than two decades before entering politics — and without compromising safety.

“I think he has a healthy caution about N.Y.P.D,” Mr. Rush said of Mr. Adams. “We have to do public safety in a way that doesn’t hurt minority communities, as it has.”

But that same relationship with the Police Department made Shahreen Akhter, a 30-year-old registered Democrat in Ozone Park, Queens, skeptical that Mr. Adams would move quickly on police reform.

She also said she worried over how he might achieve his goal of expanding the city public school system’s gifted and talented program, which Ms. Akhter said currently widened inequity among students.

Ms. Akhter’s concerns led her to cast her vote for the Socialist candidate, Cathy Rojas, instead, she said.

Audrey Dursht, a Morningside Heights resident and a former teacher, said that education was her top priority, and that her vote for Mr. Adams was a reluctant one.

Ms. Dursht, 65, added that she felt this year’s slate of mayoral candidates was “not a great selection,” but said she did not want to see Curtis Sliwa in office.

The polls in New York City are open today from 6 a.m. to 9 p.m., and voters will be choosing candidates for mayor, public advocate, comptroller, borough president, City Council and in Manhattan and Brooklyn, district attorney. They will also be voting on five potential amendments to the State Constitution.

Here are answers to questions you may have about voting.

Where can I vote?

On Election Day, you can vote only at your designated polling place, which may differ from your early voting site. Check your polling site here.

You can also call 1-866-VOTE-NYC (1-866-868-3692) — or simply 311 — to find your polling site.

I’m not sure if I’m registered. How do I check?

You can check your voting status and party registration on the New York State Board of Elections site. Once you enter your information, you will also see a preview of the ballot choices.

If you cannot find your voter registration record, contact your county’s board of elections for assistance.

Is it too late to get an absentee ballot, also known as voting by mail?

Yes, Monday was the last day to get an absentee ballot. If you’ve already gotten one, it must be postmarked by Tuesday.

I haven’t registered to vote. Is it too late?

Yes. But register to vote in future elections here.

Will interpreters be available at polling sites?

Anyone can bring their own interpreter to a polling site if needed, as long as the interpreter is not the voter’s employer or union representative.

The Board of Elections provides interpreters and materials in Spanish, Chinese, Korean and Bengali at select sites, and interpreters are available in a wider array of languages at some sites through the Civic Engagement Commission. Here’s the full list of which interpreters are scheduled to be at different sites.

Are the voting sites accessible to all?

The sites are supposed to be accessible to all voters, though a report earlier this year found many shortcomings in a survey of Manhattan locations. Voters who are visually impaired or have a disability that makes it difficult to use a pen can request ballot-marking devices that utilize audio, touch-screens, Braille and other modes.

What about people with felony convictions?

The state enacted a law in the spring restoring voting rights to people convicted of felonies who have been released on parole. People released on probation had generally already been allowed to vote. Those still incarcerated for felonies cannot vote.

Will there be ranked-choice voting?

No. Ranked-choice voting is reserved for primary and special elections for city office.

Will there be long lines?

Turnout is expected to be low, and many have already cast their ballots in early voting or by mail. But never say never.

Does voting end exactly at 9 p.m.?

No. You have the right to vote as long as you are in line by 9 p.m.

Curtis Sliwa brought a special guest with him to vote on Tuesday: Gizmo, one of the 17 cats he lives with in a studio apartment.

But Gizmo was denied entry to the polling site, on Manhattan’s Upper West Side, and Mr. Sliwa, the Republican nominee for mayor, was irate.

More problems soon followed, and Mr. Sliwa openly quarreled with election officials, shouting: “Arrest me!” when they asked him to take off a red jacket with his name on it — an apparent violation of electioneering rules.

In a general election match-up against Eric Adams that has provided relatively little drama, Mr. Sliwa’s visit to the polls created quite a stir.

His ballot jammed in the scanning machine, and the machine had to be repaired. An election worker hurled an expletive at Mr. Sliwa while asking him to leave.

“They couldn’t have been more hostile,” Mr. Sliwa said as he left the polling site, at Frank McCourt High School, more than an hour later and was reunited with Gizmo, who was being watched by a staffer.

His Democratic opponent, Mr. Adams, is heavily favored to win in a city where Democrats outnumber Republicans by nearly seven to one.

But Mr. Sliwa has received perhaps the most attention for his army of rescue cats and his animal welfare platform, and he sought to take advantage of that during his trip to the polls.

Gizmo peeked out from under a red blanket as Mr. Sliwa described how he was almost euthanized after getting a fungus.

“Gizmo was on the kill list,” Mr. Sliwa said. “Thank God my wife was able to save Gizmo.”

Mr. Sliwa, who was hit by a taxi on Friday, wore a sling on his left arm. He said he was in pain from the accident, but that he was more concerned for city workers who were placed on unpaid leave this week for refusing to get vaccinated — an issue he has increasingly focused on during the final week of the campaign.

“If I’m fortunate enough to be elected mayor, on Jan. 2, I will roll back those mandates,” he said.

Eric Adams began a day that could see him become only the second Black mayor of New York City by casting his own vote just after dawn, with a framed photograph of his late mother cradled under his arm.

Standing outside Public School 81 in Brooklyn’s Bedford-Stuyvesant neighborhood after he voted, Mr. Adams grew emotional. He traced his own improbable rise to become the overwhelming favorite in Tuesday’s election, as a working-class mother’s son who battled dyslexia and near-homelessness to become a police officer, state senator and Brooklyn borough president.

“We won already,” he said, wiping away tears. “I’m not supposed to be standing here. But because I’m standing here, everyday New Yorkers are going to realize they deserve the right to stand in this city also. This is for the little guy.”

Mr. Adams declined to weigh in on Mayor Bill de Blasio’s vaccine mandate for city workers, a far-reaching requirement that appeared to be effective at encouraging vaccination but also antagonized key unions and cast a shadow over the last days of the campaign.

Mr. Adams has been an outspoken proponent of vaccination, but his Republican opponent, Curtis Sliwa, had sought to use the mandate to stir up discontent with Democratic leadership on the eve of Election Day.

“I’m not going to get in the way of the very dangerous situation we are in right now and Monday-morning-quarterback the mayor and the union heads,” Mr. Adams told reporters. “They need to come together.”

Instead, Mr. Adams steered questions back to the themes that animated his campaign and powered his narrow victory in the crowded June Democratic primary. He painted a dire picture of New York City “battered and beaten” by violence, a pandemic and economic malaise, but promised to return the city and the Democratic Party to its working-class roots.

“The policies that I ran on, they were clear. It’s about being safe. It’s about working on behalf of blue-collar people,” Mr. Adams said. “If we abandon blue-collar Americans we’re going to lose our party. I don’t believe we’re going to do that.”

Later, in Crown Heights, where he snapped selfies for an hour with voters, Mr. Adams fielded a barrage of constituent feedback as if he was already mayor. He assured one woman he would push to set up designated marijuana smoking areas to limit the odor for nonsmokers. He told another resident he hoped to expand drumline programs for city teens.

“Don’t forget Flatbush,” shouted a passer-by who stressed the need for affordable housing in fast-gentrifying Brooklyn neighborhoods.

There was plenty of levity, too. Mr. Adams bumped fists and made promises with a wide grin. He told one couple he planned to get a dog as soon as he became mayor. When a man identifying himself as Mr. Adams’s former D.J. strolled up, Mr. Adams implored, “Let them know I had some good dance moves!”

Alvin Bragg, the Democratic nominee for Manhattan district attorney, voted in Harlem on Tuesday morning, the neighborhood where he has lived most of his life and that has served as the constant backdrop of his campaign over the last two years.

Mr. Bragg, a former federal prosecutor who is heavily favored to beat his Republican opponent, Thomas Kenniff, was welcomed by a phalanx of photographers at the Wyatt T. Walker senior housing building on Frederick Douglass Boulevard.

Inside, a handful of voters streamed in and out of a small room filled with voting booths. “Is someone important voting right now?” one asked.

Mr. Bragg, wearing a pinstriped suit, was accompanied by his wife, Jamila Ponton Bragg. “I’ve never voted in front of a crowd before,” he said, after filling out his ballot.

Afterward, on the sidewalk, Mr. Bragg reflected on the past two years, during which he has explained how his personal experiences having had a gun pointed at him — by both the police and civilians — equipped him to consider public safety and fairness in equal measure.

“If we don’t have police accountability, we won’t have safety,” he said on Tuesday.

He said that voting for himself, the first time he has done so, had been humbling.

“Just to be engaged in our democracy from this new perspective has been so important to me, so meaningful on a personal level,” he said, adding that the right to vote was under attack around the country.

Mr. Kenniff, a resident of Oyster Bay on Long Island, will not be able to vote for himself in Manhattan. He said that he planned to vote on Long Island later in the day.

After voting, Mr. Bragg drove to a polling place on 134th Street, where he was greeted by Jumaane D. Williams, the city public advocate; and Cordell Cleare, a Democratic State Senate candidate.

Upon seeing Mr. Bragg, Mr. Williams offered an enthusiastic greeting: “The D.A. is here!”

The winner of Tuesday’s election for Manhattan district attorney will become only the third person to hold the position in more than 40 years, taking over a prosecutor’s office that is one of the most prominent in the country.

The district attorney’s office handles tens of thousands of cases a year and is conducting a number of high-profile investigations, including one into former President Donald J. Trump and his family business that has resulted in the indictment of the company and one of its top executives.

If Alvin Bragg, the heavily favored Democratic nominee, prevails, he will become the first Black head of the Manhattan district attorney’s office. Mr. Bragg, a former federal prosecutor and a chief deputy at the New York State attorney general’s office, has throughout his campaign drawn on his biography to explain his policies, which he has said balance public safety with fairness for all defendants.

The office prosecutes a disproportionate number of Black men, and many of Mr. Bragg’s supporters have said that his personal experiences would help transform its work, moving its focus away from low-level crimes and toward gun trafficking, economic crime and public corruption.

His Republican opponent, Thomas Kenniff, a veteran of the Iraq war and a defense lawyer, provides a sharp contrast: Mr. Kenniff is looking to crack down on low-level misdemeanors including fare-beating and graffiti. He believes that doing so will lower the overall crime rate.

Mr. Kenniff, who was a longtime resident of Manhattan before moving to Long Island several years ago, has said he would move back to the city if he were to win on Tuesday.

Mr. Bragg has said that in his time at the attorney general’s office, he sued the Trump administration “more than 100 times,” but he has also said that those cases were separate from the district attorney’s investigation that he would inherit.

Mr. Kenniff said that if he were to find that the former president had committed any crime, he would “absolutely” prosecute the case, and that he did not agree with Mr. Trump’s contention that the investigation was a form of political persecution.

There are five proposed constitutional amendments on the ballot, asking voters to decide on measures involving legislative redistricting, changes to voting laws, environmental policy and New York City’s civil courts. Those that are approved would take effect on Jan. 1, 2022.

Here’s a quick rundown of the five ballot measures.

1. Changes to the state’s redistricting process

This measure involves the drawing of legislative maps, which occurs every 10 years. It also proposes other changes such as capping the number of state senators at 63 and counting incarcerated people at their last place of residence rather than where they are detained.

Under the measure, only a simple majority vote among state lawmakers — rather than the current two-thirds — would be required to pass redistricting plans. Opponents have argued this change could diminish a minority party’s voting power, though others have said it’s too early to predict that.

2. An environmental rights amendment

This measure would give New Yorkers a constitutional right to clean air, water and a “healthful environment.” The proposal language is vague on what a “healthful environment” is or how the standard would be legally enforced.

Critics have cited the measure’s broad language as a concern, arguing that the lack of specificity could lead to unnecessary lawsuits. But environmental advocates have said the proposal’s language only poses a risk to those who may be polluting the environment.

3. A push to allow same-day voter registration

The measure, one of two ballot proposals related to voting rights, would eliminate a rule that requires voters to register at least 10 days before an election.

If passed, the measure would make it possible for state lawmakers to adopt same-day voter registration, something 20 states already have done. This measure would be particularly beneficial to voters who do not start paying attention to local politics until late in the election cycle, supporters have said.

4. Making it easier to cast absentee ballots

The second proposed change to the voting process would erase the requirement that those who request absentee ballots explain why they need them.

Under current law, mail-in ballots are only allowed for voters who expect to be away on Election Day, or who have an illness or disability that would prevent them from voting in person.

5. Changes to New York City’s civil courts

This measure would double the monetary limit for claims filed in New York City’s civil courts from $25,000 to $50,000. This would enable the courts to consider more small claims, reducing the caseload for the state’s Supreme Court.

Although the change would be likely to increase the efficiency with which lawsuits are resolved, it might also increase the workload for the city’s understaffed civil courts.

In New York City, a global beacon that draws a diverse population from all over the world, the City Council has never had a person of South Asian descent among its membership.

No openly gay Black woman has ever sat among its 51 lawmakers, even as the city has long been a haven for L.G.B.T.Q. people of color, and no Muslim woman has served as a council member in a city with an estimated 769,000 Muslims.

But after the polls close tonight, those barriers are all widely expected to be broken by a number of Democratic candidates who, in a city where Democrats outnumber Republicans nearly seven to one, are heavily favored to win their elections.

Shahana Hanif, a former City Council employee who won her primary in a Brooklyn district that covers Park Slope, Kensington and parts of central Brooklyn, is expected to be the first Muslim woman elected to the Council in its history.

Ms. Hanif, who is Bangladeshi American, will also be one of the first Council members of South Asian descent, along with Shekar Krishnan, who is of Indian descent and won his primary in Jackson Heights and Elmhurst, in Queens. If Felicia Singh, who is in a competitive race against a Republican opponent in Queens, wins her election, she will join them.

The City Council is also expected to have its first out gay Black women serve as members: Kristin Richardson Jordan in Harlem and Crystal Hudson in a Brooklyn district that encompasses parts of Prospect Heights, Crown Heights, Fort Greene, Clinton Hill, and Bedford-Stuyvesant.

A number of other L.G.B.T.Q. candidates are likely to join them, including Tiffany Cabán and Lynn Schulman in Queens; Chi Ossé in Brooklyn; and Erik Bottcher in Manhattan.

They are part of a larger shift in New York’s City Council, which is poised to have a diversity that mirrors the city it represents. More than two dozen women are positioned to take a majority of the Council’s seats, for the first time ever.

By nearly every metric, the Republican Party has been wiped out in the nation’s largest city.

But in a handful of City Council races, there are still signs of Republican life.

In southern Brooklyn, Inna Vernikov, a Republican, has the backing of Donald Trump Jr. as she works to coax voters who back Republican candidates for president to do the same in District 48, which includes Brighton Beach, Manhattan Beach and parts of Midwood and Sheepshead Bay.

Her Democratic opponent, Steven Saperstein, a former Republican, has declined to say how he voted for president last year, insisting that at the local level, even the many pro-Trump voters who live in that district are more focused on municipal matters.

Indeed, for years, New York City voters who favored Republicans for president often still elected Democrats in local races. But in the final days of the fall campaign, Republicans are working to change that pattern in the district, which is home to many Orthodox Jews and Russian and Ukrainian immigrants.

If they succeed, that victory will offer one more example of just how polarized, and nationalized, even ultra-local American politics has become.

There is also a high-profile and competitive race unfolding in Queens, in a district that is the last Republican-held seat in that borough.

Felicia Singh, a Democrat and a teacher who is endorsed by the left-wing Working Families Party, is running in District 32 against Joann Ariola, the chairwoman of the Queens Republican Party. The race has stirred considerable interest from the left and the right, has attracted spending from outside groups and has grown increasingly ugly in its final days.

The other race widely seen as competitive is in District 50 on Staten Island, for a seat held by the Republican minority leader, Steven Matteo.

David Carr, Mr. Matteo’s chief of staff, is the Republican nominee; Sal F. Albanese, once a Brooklyn city councilman who has run unsuccessfully for mayor several times, is the Democratic nominee; George Wonica, a real estate agent, is running on the Conservative Party line.

Unlike in the Queens race, where there is a clear ideological contrast, the candidates on Staten Island largely agree on several issues: They oppose city vaccine mandates and strongly support law enforcement.

There is always the possibility of a sleeper race becoming closer than expected.

“Low-turnout elections are always where surprises happen, and we’ve had a bunch of those in the past few years,” said Kevin Elkins, the political director for the New York City District Council of Carpenters, which is largely supporting Democratic candidates but backs Ms. Ariola.

“Most of the elected officials and candidates who have run before have no interest in being next on that list.”