Mayors tend to occupy a permanent part of New York City’s physical, or mental, landscape. There’s an airport named after Fiorello La Guardia, while New York University has a graduate school that memorializes Robert Wagner. The East River crossing at 59th Street is now the Ed Koch Bridge and the hub of the city bureaucracy has been renamed the David Dinkins Municipal Building. Rudy Giuliani, Abe Beame, and John Lindsay may not have eponymous physical monuments—yet—but their names, for better or worse, define eras.

History has not been as gracious to the mayor’s counterpart in government, the City Council, which passes the laws he gets to sign and the budget that funds the programs and projects that flesh out his legacy. Three consecutive City Council speakers have run for mayor—Peter Vallone in 2001, Gifford Miller in 2005, and Christine Quinn in 2013—and all have fallen well short. The current speaker, Melissa Mark-Viverito, will leave public life at year’s end with no clear political future. When the Quinnipiac Poll asked New Yorkers in July whether or not they approved of the job she was doing, two in five respondents didn’t know enough about her to answer.

That’s too bad, because there’s a lot to know. While the New York City of the future will remember Bill de Blasio—with fondness, with regret, with his name on a Staten Island ferry or a certain Park Slope gym—a large share of the credit for his deeds during his first term will belong to Mark-Viverito and the council.

To be sure, de Blasio’s own words and deeds have been vitally important to creating a new era after 20 years of Republican rule. And yes, the mayor’s signature policy achievement—the creation of a universal pre-kindergarten program—was made possible by a budget decision in Albany, not City Hall.

But virtually every other feature of the de Blasio administration’s first term has been shaped by or reflected in the mayor’s interaction with the council. Its members have approved and funded critical elements of his agenda and pushed him to take up other issues that became points of pride in his program. By many accounts, it has been the most progressive council in recent memory, perhaps far longer—although it stopped short precisely in the areas where progressive advocates believe de Blasio failed to meet expectations.

In a few weeks’ time, the mayor will be inaugurated again. The council is likely to be as important to his second term as it was to his first—but, for a lot of reasons, it will be a very different body from the one de Blasio has been used to dealing with. Whether we’re looking backward or ahead, understanding the council’s role in de Blasio’s New York is essential to grasping whether and how, in an urban environment, progressive ideals get translated into concrete policy.

New York’s City Council has 51 members elected from districts with populations of 160,000 or so—each the size of a small city. They’re usually elected in the same quadrennial elections that put the mayor, public advocate, and other municipal officials in office (though sometimes when new Census numbers lead to redistricting there are midterm elections). Each member makes a base salary of $148,500, has a staff of seven or so people, sits on a few committees and dispenses several million dollars in discretionary funds to community groups or for capital improvements to their districts. Under current law, members are limited to being elected to two full terms, but several current members are covered by the Bloomberg-engineered term-limit relaxation, and so are either wrapping up a third and final term now or will start one come January 1.

The council passes city laws, approves the budget, and has broad power over changes in land use, like whether to rezone a neighborhood or sell off a city-owned parcel of land. Usually home to no more than a handful of Republicans, the council operates generally by consensus, with most members never or very rarely voting “no” on a measure that has made it to the floor. That lack of internal debate and the limitations on the council’s ability to affect day-to-day city operations—coupled with the council’s occasionally performing fluffy ceremonial duties like co-naming streets after noteworthy citizens—has led some local players to dismiss the body as a minor character in the city’s ongoing political epic. One former member once said the Council was worse than a rubber stamp, because at least a rubber stamp leaves an impression.

The reality is more complex, however, with the council’s role shaped as much by the city’s political era as the personalities and ambitions of its members. Before term limits kicked in in 2001, for instance, the body featured a number of skilled and principled legislators picking their way amid abundant pieces of deadwood. Under Vallone, a deeply decent public servant whom no one ever mistook for a progressive, a few individual councilmembers succeeded in waging fierce resistance to Mayor Giuliani. After Bloomberg was elected, Speaker Miller tried to vie with the billionaire mayor but Bloomberg’s deal-making prowess helped him undercut the council leader. Christine Quinn, speaker from 2006 through 2013, resisted the mayor on occasion but largely accommodated him—most infamously on the 2008 vote loosening term limits.

When de Blasio took power, it marked the first time the Democratic council would work with a Democratic mayor in a generation. It also marked the first time progressives controlled both sides of City Hall since at least 1973, thanks in part to the rise of the council’s Progressive Caucus, which was launched in 2009, quickly swelled to 19 members in 2013, and has since been a major force in the chamber.

It was clear from the earliest moments of the de Blasio era that the mayor viewed that as a unique opportunity. Swimming in political capital after his landslide election, the mayor—clearly wanting an ideological soulmate to work with—took an extraordinarily overt role in getting Mark-Viverito elected speaker. Sources differ on whether the mayor’s help was decisive in Mark-Viverito’s winning the job, but there’s no denying he played an important role.

The results have been notable. Mark-Viverito boasts that, in her four years as speaker, the city legislature has passed more bills than in any other session. The council dramatically enlarged a right to paid sick leave, expanded living-wage requirements and launched a municipal identification card that undocumented immigrants could receive. It passed a mandatory inclusionary housing rule to force developers taking advantage of newly authorized density to set aside some apartments for targeted income groups, took steps to protect freelancers, outlawed most uses of credit-checks for job applicants, and made either-sex bathrooms the law of the city. The council limited the NYPD’s and city jails’ cooperation with federal immigration officials, provided legal help to tenants fighting their landlords, and funded free lawyers for detained immigrants fighting deportation.

“This has been a very progressive council,” says Johanna Miller, advocacy director for the New York Civil Liberties Union (NYCLU).

“It’s been an incredibly effective and productive session, both for the mayor and for us in terms of what we were able to do,” Mark-Viverito says. “We’ve really moved forward a progressive agenda.”

Mark-Viverito also took steps to reform the council itself. She hired more bill-drafting staff to clear up a bottleneck that had slowed down members’ proposals, and rationalized the amount of discretionary money members were allowed to spend each year: Where the dollar figure was once a political decision by the speaker, it’s now based on the prevalence of poverty in each district. Committee chairpersons gained more power. Councilmembers got a generous raise, but outside income was, for the first time, banned. More and more districts took up participatory budgeting, where residents get to decide how to spend $1 million or more in capital money each year. And the council became more transparent, with all its hearings webcast live and extensive video archives.

Still, not everyone is thrilled with the council’s performance. Some environmental advocates feel lawmakers have done a poor job holding the mayor accountable for his promises on reducing greenhouse gases. And at press time, the council is still tinkering with a measure to cap the amount of garbage that waste-transfer stations in any neighborhood has to accept. It’s a longstanding environmental-justice concern that is apparently stalled over the law’s potential impact on particular waste-management companies.

Meanwhile, advocates for low-income New Yorkers were disappointed that the council didn’t do more to budget for a “fair fares” program to offer discount transit fares for the poor. Civil libertarians are scandalized over the bill to fund security guards for religious schools, a bit of pandering that clearly breaches the church/state wall that Donna Lieberman, the executive director of the NYCLU, calls “a blatant political payday for a group that hadn’t even asked for it.” Some in the housing world wish the council had pushed harder to get lower-income groups a bigger share of the mayor’s housing plan.

Antonio Reynoso, a Brooklyn councilmember, says he’s proud of what the body has done, but sometimes wishes that it had pushed harder faster. “When you see that Donald Trump got elected last year, it put into perspective the first three years and how much more we could have done to make sure the neediest people are supported in New York City,” he says. “It changes your perspective.”

One striking thing about this council is not something it accomplished, but something it didn’t. During Rudy Giuliani’s last term, which ran from 1998 through 2001, he vetoed 22 pieces of council legislation. Over Bloomberg’s dozen years in power, he issued 78 vetoes. For his part, de Blasio has yet to veto a single bill. That could mean he and the council simply have a great relationship. Or it could mean the body simply hasn’t pushed him hard enough.

Mark-Viverito describes the relationship as productive. “I differ with the mayor when we need to differ. Look, we are philosophically aligned. We both wanted to build a more inclusive city. Now, on how we get there, we may differ,” she says. “Having a number of vetoes is not reflective of whether you’re an effective legislative body.”

There have been places where the council has resisted the mayor. It made clear, for instance, that it would not go along with a ban on carriage horses in Central Park. And there have been places where they pushed de Blasio, like regulating how much a fast-food restaurant can change workers’ schedules or establishing the right to counsel for low-income tenants in housing court. “They really pushed the mayor on that,” says Giselle Routhier, policy director for the Coalition for the Homeless. “It’s not something the mayor would have done without the strong support of the council.”

But one council insider, articulating a broader feeling, says there is some frustration that despite Mark-Viverito’s moves to make the body more democratic, the council still seems highly centralized. “The problem in the council for the entire session is that no bills come to the floor unless there has been negotiation with the mayor’s office. The speaker’s office and mayor are working hand and hand.” One advocate puts it this way: “There just hasn’t been any real push and pull. They didn’t pass any bill the mayor didn’t want.”

Mark-Viverito disputes the contention that her office excludes members from negotiations with the administration over bills. Her allies say that criticism misses the point altogether.

“We are broadly very well aligned, and it is generally better to reach agreement,” says Brad Lander, a Brooklyn councilman and one of the founders of the Progressive Caucus. He notes that, because of the city’s strong mayor system, the council has difficulty imposing its will on the mayor. Bloomberg, for instance, sued to avoid having to enforce a living-wage law or to follow a law against police profiling and regularly refused to baseline budget priorities that the council thought they’d won the previous year.

Under de Blasio, the council negotiated for years to finally win a “certificate of no harassment” program to prevent landlords who have mistreated tenants from getting permits to renovate or build new residential buildings. “Could we have passed that earlier in the term, without an agreement? And overridden a mayoral veto? There would not have been any value to that,” Lander says, because the mayor could simply have failed to adequately enforce it.

The question, says Queens Councilman Rory Lancman, often a thorn in de Blasio’s side, is “what does it mean to have a check and a balance on a mayor whose policies you generally support?”

“The body as a whole I think has been cautious about exposing the mayor and our joint progressive project to unfair scrutiny,” Lancman says. “Editorial boards and others want to see our agenda fail. As a Democratic speaker and a Democratic mayor, every effort was always made to try to reach agreement with the administration on a bill to avoid it becoming a source of conflict.”

“There are innumerable pushes and pulls at any level of government,” he continues. “How the council navigates that is really what determines how much power they have vis-à-vis the executive.”

No subject area better reflects the complicated dynamics of this council’s role than public safety. While praising the council’s overall record, the NYCLU’s Miller says, “I think the one place where we’ve been less excited is that there’s a lot less appetite for taking on the NYPD than a lot of us expected.”

The body certainly has posted some successes in the criminal-justice reform arena. The council in 2014 passed bills placing strict limits on when city police or correction officers can honor federal immigration detainers for people in custody. In 2016, it changed the way the NYPD handles minor offenses like public urination and littering, requiring the issuance of civil summonses instead of arrests in many cases.

But there have also been retreats and failures. When the council passed the law creating New York City’s municipal ID card, it included, at the NYPD’s insistence, a measure to retain applicant documents until the end of 2016. Immigration advocates resisted that clause, worried it could create a way for the feds to track down undocumented people. Sure enough, after Trump’s election, two Republican assemblymembers from Staten Island sued to prevent the city from destroying the documents. While there have been key rulings in the city’s favor, the case is still pending.

The council never acted to pass a bill Lancman proposed outlawing the kind of chokehold that led to Eric Garner’s death at a detective’s hands in 2014. It has sat on a bill that would have required the NYPD to report about the kinds of digital surveillance equipment it is using and what safeguards are in place to protect residents’ privacy.

Most controversial has been the “right to know act,” a package of bills that would require police officers to identify themselves personally to people they stop and to inform civilians that they have the right to refuse a police search under some circumstances. Mark-Viverito struck a deal with police officials to impose the policies through NYPD orders, not legislation, but her members kept pushing. Both bills long had more than enough votes for passage, but negotiations dragged on—largely because the NYPD was resistant to the bills and the council was unwilling to ram it down its throat.

“You don’t want to have them do it disgruntledly,” says Reynoso, a sponsor of one of the measures. “The rollout is much stronger. The ideal situation is that the NYPD be happy with it—that they at least respect it.”

Critics, however, think this sounds like an agency having de factor veto power over the lawmakers who oversee it. “The NYPD shouldn’t operate as an independent legislative body,” Miller says.

Just this week the Council announced a compromise in which cops will only have to provide their business card in certain kinds of stops. One of the leading advocacy groups, Communities United for Police Reform, was furious about the compromise, urging the Council to reject “this loophole-dominated bill and continue to support the passage of the real Right to Know Act.”

Still, Mark-Viverito will be remembered as the person who, along with a smart and scrappy ground of advocates, turned the closure of Rikers Island from flaky idea into a mayoral commitment. De Blasio dismissed the idea up and down, but the speaker convened a blue-ribbon panel that issued a bold and thorough report, all but forcing the mayor’s hand. “He didn’t see a path. I saw a path and I was able to show that path,” the speaker says of de Blasio.

“But for the council, I don’t think we’d be on the path to closing Rikers,” Lander says. “I don’t think a different speaker would have had the courage to both establish that commission and establish that commission when the mayor is not there.”

One question for 2018 and beyond is what the new council will do to push the city toward actually shutter its island jails.

There are eight people running to succeed Mark-Viverito as speaker. All are men. That reflects a growing gender gap on the council: Come January 1, the number of women in the city legislature will fall from 13 to 11 (the high, roughly a decade ago, was 18). It’s an alarming development in an era when the perils of male hegemony are the stuff of daily headlines. But it’s not the only big change looming.

While the council and de Blasio have had their differences since 2014, the relationship has been generally low on drama and high on partnership. Compared to earlier eras, very few councilmembers have made regular headlines by railing against the mayor or speaker. That reflected the political landscape: De Blasio was an incumbent very likely to be reelected, and councilmembers also had little incentive to rock the boat too violently given their likely reelection. Incumbency was the warm and fuzzy blanket that made the 2017 elections largely free of friction or suspense.

In four years’ time, however, term limits will force the mayor, the other city- and borough-wide officials, and three-quarters of the council out of office. That raises the stakes for all of them.

“Politically speaking, people are going to be out for themselves,” says Lancman, though he clarifies that this doesn’t necessarily mean they’ll behave without principle. “Every term-limited councilmember has to be and is mindful that this might be their last four years in public life. I think folks will much more feel the fierce urgency of now.”

That is the hope of advocates, too. Many praise the outgoing council for setting a new standard for progressive government. But they know the to-do list is long and this rare political moment in New York—when a progressive mayor and a progressive council are in power and an expanding economy (and tax base) is giving them room to work—won’t last forever. Some, like the NYCLU, hope that the council will be more aggressive in using its oversight powers, including the right to subpoena city officials to get answers. Others have their hopes set on new legislative achievements.

“We are really hopeful that it will be more fertile ground,” says Maya Bhardwaj of Faith in New York, a progressive coalition. “We’re hoping that folks are thinking about their legacy.”