FORTUNE — The New York City Council on Wednesday voted 46-5 on a bill to expand the city’s paid sick leave, guaranteeing that 1.2 million workers can call in sick without losing pay.
The measure, which covers more workers than any other similar protection in the U.S., will likely be the first bill New York City Mayor Bill de Blasio signs into law. “From waitresses and dishwashers to store clerks and car wash workers, New Yorkers across the five boroughs will finally have legal protection to a basic right that so many of us take for granted,” he said after the council’s vote.
That’s a right that more workers across the country are vying for, and securing.
Last year, Portland passed a paid sick leave bill, as did Jersey City, N.J. New York City passed initial legislation that applied to employers with 15 or more workers (Wednesday’s vote lowered that threshold to five), and Washington, D.C. expanded the sick leave protection it first passed in 2008.
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This year, in addition to NYC’s vote on Wednesday, Newark has passed a law mandating paid sick leave. Citywide measures are being considered in Eugene, Ore. and Tacoma, Wash., and statewide initiatives are pending in Vermont and Massachusetts.
All told, existing paid sick leave laws cover 2.1 million Americans, according to Ellen Bravo, executive director of Family Values@Work.
“Two things are happening,” says Bravo. As these initiatives are passed, “workers in other cities say, ‘This would really make a difference in my life. If they can do it in fill-in-the-blank, we should do it as well.’” The second factor is “elected officials [are] recognizing that they should be on the side of the economy that works for everyone not just for the few.”
Despite the recent legislative success, some 40 million American still have to make the choice between going to work sick and missing out on pay. The absence of federal legislation ensuring paid sick leave is a vestige of a time when only one parent worked while the other provided primary care to children and older adults, according to a report by the Economic Policy Institute.
The push for paid sick days grew out of the Family and Medical Leave Act, which was enacted in 1993, says Bravo. The law guaranteed that workers could take time off for the birth of a child or to care for an ill relative, but it didn’t allow for a paid day off if they or their child caught the flu. A 2010 report by the National Opinion Research Center illustrates the tough choice that parents without paid sick days must make: They are twice as likely to send a sick child to school and are fives times as likely to take a child or relative to the emergency room because they can’t take time off during the day for a doctor’s visit.
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Senator Edward Kennedy first called on Congress to address the issue when he introduced the Healthy Families Act in 2004, but it went nowhere. Senator Tom Harkin and Representative Rosa DeLauro reintroduced the measure in 2013. Those bills are in committee.
But as federal initiatives run into headwinds, local paid sick leave measures have found success. Paid sick leave first became law in San Francisco in 2006 after a group of restaurant workers pushed for a ballot initiative to establish the protection, which voters passed by 61%. Connecticut became the first — and, at present, only — state to pass paid sick leave in 2011.
And the fight for paid sick leave has gained even more steam recently as income inequality gains increased national attention.
Access to paid sick time is unevenly distributed throughout the workplace, with higher wage employees far more likely to have such benefits. According to the EPI, 86% of workers who make more than $37 an hour have paid sick days, compared with 19% of those who make $8.10 or less. A two-child family with a single working parent earning $10 an hour without paid sick time cannot miss more than three days of work in a month without falling below the federal poverty line, according to a 2011 report from the EPI.
Granted, paid sick leave has plenty of vocal, adamant opponents.
Concerns over what paid sick leave could mean for small businesses owners have led to what Vicki Shabo, director of work and family programs at the National Partnership for Women & Families, calls a “counter trend” — legislatures enacting laws against paid sick leave before support for the measure can take hold. As of November 2013, 10 states had adopted laws that ban any city or county within the state from establishing sick leave protection, the EPI says. The most notable case is Wisconsin, where legislators repealed Milwaukee’s sick leave law in 2011 even though it had passed by ballot initiative in 2008 with 69% support. On Wednesday, Republican Councilman Eric Ulrich said he voted against the expansion of NYC’s paid sick leave since it would “hurt people who work hard and play by the rules.”
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Research on the topic doesn’t support that position. According to a 2011 study by the Institute for Women’s Policy Research on San Francisco’s paid sick leave ordinance, more than two in three businesses in the city support the law and six in seven employers reported no negative impact on profitability. The EPI examined the NYC law and found that if all employees used all five paid sick days, the cost to an employer that had previously not provided paid sick days ranged by sector from 0.12% to 0.92% of annual sales. Employers also stand to save on replacing workers since having paid sick time reduces voluntary job mobility by 5.6 percentage points for married men and 3.6 percentage points for married women.
Opposition to paid sick leave is “a knee-jerk, don’t-tell-us-what-to-do reaction,” Bravo says, “since it’s hard to argue that people should come to work sick or lose pay.”
