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.