New Year's may be an arbitrary time to take stock of where a city's gone or going, but it has a shred more significance in New York City than elsewhere, and not just because the big glass ball drops in our Times Square.

January 1 is New Year's Day everywhere, but in the five boroughs it's also the anniversary of the Great Consolidation—the day in 1898 when the existing City of New York (Manhattan and the west Bronx) joined with Brooklyn, Queens, Staten Island and the east Bronx to form the modern metropolis.

So, as 2012 turns to 2013 and New York celebrates its 115th year as a unified city, here are 10 stories from the past year that are most likely to shape life in New York over the coming 12 months:

10. The mayoral race begins

It isn't often that the city decides how to replace a billionaire, three-term mayor, and the long journey toward that decision was clearly underway by the fall of 2012. With publisher Tom Allon, Public Advocate Bill deBlasio, supermarket mogul John Catsimatidis, Comptroller John Liu, nonprofit executive George McDonald, City Council speaker Christine Quinn, and former comptroller and 2009 Democratic nominee William Thompson already in the race, former Councilman Sal Albanese, former Bronx Borough President Adolfo Carrion, and MTA boss Joe Lhota jumped in, and Manhattan Borough President Scott Stringer jumped out (opting to run for comptroller instead). Meanwhile, Bronx Beep Ruben Diaz said he won't run for public advocate; Diaz's exit from the citywide campaign, and Carrion's entrance into it, raise all sorts of questions about the state of Latino political aspiration in the city, which we explored in detail here.

9. Hospital closings

Several of the city's medical centers felt the impact of both short-term and long-term crises in 2012. At least five (New York Downtown, NYU Langone, Bellevue, Manhattan Veterans and Coney Island Hospital) closed in advance or in the wake of Hurricane Sandy, leaving no Level 1 trauma centers open below 32nd Street, according to the city's Independent Budget Office—which also noted that eight of the city's 62 hospitals are in or adjacent to hurricane evacuation zone A. This raised obvious questions about the medical system's resilience to future coastal storms. But hospitals on high ground were weathering a different storm: the harsh math of modern hospital finance. Peninsula Hospital in the Rockaways closed. Interfaith Medical Center in Brooklyn declared bankruptcy. And according to our reporting, at least five other Brooklyn hospitals could merge or close.

8. Atlantic Yards opens

After all the promises, subsidies, lawsuits, delays and changes to the building plan, the Barclays Arena—anchor tenant of the most acrimonious development episode in New York City since Westway—opened in September. But with the rest of the residential and office development at the site still to come, the debate continues over whether Atlantic Yards will improve or ruin its neighborhood. What's already certain is that the AY saga was always about more than what to do in and around a utilitarian-looking railyard on Flatbush Avenue. It was about the city's land-use process (which the Atlantic Yards project bypassed), the Bloomberg administration's commitment to “affordable housing" (a term whose fluidity was exposed in a behind-the-scenes tussle between Forest City Ratner and city housing officials) and the vagaries of the real-estate market. Conceived during the development boom, downsized during the financial-crisis bust, it remains to be see how large the Atlantic Yards complex—whose size was always part of its allure or danger, depending on where one stood—ends up being.

7. The jobs mystery

After the 2007 recession hit Mayor Bloomberg certainly delivered his share of bad news, announcing round after round of budget adjustments to reflect the reality of lower tax revenue. But from 2009 on City Hall has depicted the city's economy as outperforming expectations and the rest of the country—enduring a shallower and shorter recession than the country as a whole, while creating an impressive number of new jobs. As recently as May, the mayor hailed private-sector job gains as “the best in 60 years." Increases in the unemployment rate were explained as the result of job seekers—inspired by the robust recovery—flooding the city's labor market.

Over the summer, however, a disparity emerged in the jobs numbers: The number of jobs the city said had been created weren't reflected in the number of residents who said they were employed. For instance, in November the state Labor Department said New York City had gained 66,200 jobs over the past year. But according to the federal Bureau of Labor Statistics, the number of people saying they are “employed" rose only 20,000 over the course of the year. Where were the other 46,000 jobs going? Some speculated that commuters were taking more of the jobs; others wondered if people were doubling up on positions. The fact that the jobs numbers come from an employer survey, while the employment numbers are generated by a household poll, could explain the mismatch.

In any case, the city's unemployment rate dipped in November to 8.8 percent, but that was still higher than the nation's 7.7 percent rate. And while a job is better than no job, it's worth noting that most of the city's job creation was in low-wage service sectors.

6. Rising homelessness

Even before Sandy, the number of people in New York City's homeless shelters was at record numbers. As of Christmas Eve there were 47,336 people in the shelters, including just under 10,000 families with children. Over the first five months of the current fiscal year, the number of families with kids in the system averaged 15 percent higher than the same month in 2011. And back in January, the city's survey of homeless people not in shelters—the “street homeless"—found an uptick for only the second time in seven years. The mayor attributed the rising shelter census to the fact that “We have made our shelter system so much better that, unfortunately, when people are in it — or fortunately, depending on what your objective is — it is a much more pleasurable experience than they ever had before," but others pointed to the disappearance of the Work Advantage transitional housing program and continued softness in the labor market as more likely causes.

5. School reforms stutter

As the final graduating class of Bloomberg's mayoralty headed to senior year this fall, there were new questions about the strength of the progress made by schools under mayoral control. Students in grades 3 through 8 made modest gains on their standardized tests, but the high-school graduation rate was flat after several years of gains, a court stopped the city from closing several “failing" schools and new research pointed to startling disparities among neighborhoods in how well-prepared high-school graduates are for the demands of college. The news wasn't all disappointing: For one thing, earlier in the year a study found that the small high schools that have been the linchpin of the administration's high-school strategy post higher graduation rates than other schools. And the city prevailed in its push to release teacher evaluation scores, although that didn't put to rest long-standing concerns about what the scores actually mean. Taken together, 2012's school news provided plenty of grist for mayoral campaigns looking to craft a new education agenda. But it's unclear that any of the candidates plan to discuss radical changes.

4. Stop and frisk slows down

After years of rising numbers of encounters between police and people on the street—most of whom are men of color found to have been doing nothing illegal—intense political pressure forced the city to scale back its “stop-and-frisk" policy last spring. According to a study by the New York Civil Liberties Union, there were 30 percent fewer stops in the first nine months of 2012 than in that period in 2011. A spike in shootings over the summer led some to speculate that less-aggressive policing was going to result in higher crime. But as of December 9 crime was up a modest 3.3 percent over the year, led by a 9 percent increase in grand larceny, with the number of murders down 21 percent. The frisking controversy touched off a related debate about the city's policy of arresting people for criminal trespass, and inspired the City Council to propose a battery of new laws for reining in the NYPD. Beyond the headline numbers on stops or crime, the question of how police should act in high-neighborhoods is complex, as we found in our reporting in East New York, the epicenter of stops.

3. 2012 elections

As the presidential race came and went, New York felt like the sideline of what was really a contest over Ohio, Florida and a handful of other states. But the impact of the campaign season on the city was obvious and multifaceted. The president's re-election victory at least theoretically holds out the prospect of urban-friendly policies in the second term; meanwhile, post-election Republican self-examination could encourage a more robust competition for urban votes in future races. Victories by Democrats in State Senate races would have elevated city legislators to the majority, but a breakaway faction led by the Bronx's Jeff Klein shifted the landscape. A once-again controversial redistricting process altered congressional lines in a way that invited State Sen. Adriano Espaillat to challenge—and nearly beat—veteran Rep. Charles Rangel, in a race that highlighted continuing problems with the city's voting system. And with Secretary Hilary Clinton stepping away from the State Department and Gov. Andrew Cuomo continuing to enjoy high approval numbers in Albany, the speculative season for the 2016 race will have New York anywhere but on the sidelines.

2. Shootings

Whether it's the Aurora theater tragedy, the Sikh temple murders, the Sandy Hook school massacre, the slaying of firefighters in upstate Webster or the killing of Trayvon Martin in Florida, gun violence was a more constant presence in headlines this year than ever before. The highest-profile events happened outside the city. But from the incident outside the Empire State Building in August, to the alleged serial killer who shot three shopkeepers in Brooklyn over several months, to the murder of a mother outside a hospital earlier this month, New York suffered from plenty of gun violence. And now that the Newtown tragedy has revived the debate over gun control, New York City—with its tough gun laws, vulnerability to gun violence and anti-gun mayor—will be a prominent player in the national conversation to come. Another big player? The gun industry, which often lurks in the background of gun politics as the NRA takes all the heat.

1. Sandy

When the National Hurricane Center issued an advisory on Monday, October 22nd, about “tropical depression 18" and its threat to Jamaica, who would have predicted that by the following Monday evening New York City's Notify NYC text messaging service was going to issue an alert saying that “residents are being instructed to go indoors immediately and to remain indoors until further notice," or that by the next morning, life along huge sections of the city's coastline would have been altered so dramatically?

It's just as hard to predict what long-term effect the storm will have on those neighborhoods or on how the city approaches waterfront development, emergency operations or preparing for climate change. Will the recovery effort and questions about sea walls and tidal gates dominate the 2013 campaign? Will the marketplace force a scaling-back of waterfront development plans before city officials can decide whether they want to do so? And after the threat of Irene in 2011 and the reality of Sandy in 2012, what will the next tropical storm season bring?

We won't dare to guess, except to say that in 2013 and beyond, city residents aren't going to look quite the same way at run-of-the-mill tropical depressions, however distant or nameless they are.