Last week, the Supreme Court upheld a core provision of the Affordable Care Act, quashing the Republican Party’s latest attempt to gut the law through the judicial system. At issue in the case, King v. Burwell, was the government’s ability to provide subsidies to help millions of working Americans purchase health insurance through the federal exchange. Yet, as too many middle-class families know, health insurance is only one of the costs associated with getting sick. For more than 40 million workers who currently lack paid sick leave, another pressing concern is how to afford taking time off.

As the court was preparing to rule on the Affordable Care Act, in nearby Montgomery County, the county council was passing one of the strongest paid sick-leave laws in the nation. The measure, which passed last Tuesday by a 9-0 margin, requires most employers in the county to provide at least one hour of paid sick leave per 30 hours worked. When the legislation takes effect next year, it will benefit an estimated 90,000 private-sector workers who currently do not receive any paid time off. With the bill’s passage, Montgomery County becomes the 23rd place in the nation to guarantee paid sick days and the fifth since 2015.

To appreciate the momentum for paid sick leave, however, it’s necessary to understand how we got here. The recent passage of multiple laws in rapid succession belies a long struggle to get politicians to take up the cause, even within the ranks of the Democratic Party. Indeed, a closer examination reveals the anatomy of a legislative movement and demonstrates how grassroots pressure can turn what some considered a fringe issue into a political juggernaut.

A decade ago, there was not a single paid sick leave law anywhere in the United States. In 2006, San Francisco approved the country’s first such measure by ballot initiative. That year, Democrats also regained control of Congress, fueling predictions that paid sick leave would become a hot topic of debate at the federal level. But legislation introduced by the late Sen. Ted Kennedy (D-Mass.) and Rep. Rosa DeLauro (D-Conn.) didn’t have sufficient support among Democrats to pass and never came to the floor for a vote. Since then, a hard-fought grassroots campaign has turned paid sick leave into a mainstream issue, and a national paid sick days law could easily be in the cards for the next Democratic Congress.

The fight began in earnest in 2007, when the Working Families Party, along with other progressive groups and labor organizations, began pushing for statewide legislation in Connecticut. For the next four legislative sessions, enough Democratic leaders sided with corporate interests to prevent a bill from reaching the governor’s desk. The turning point didn’t come until 2010, when paid sick leave became a contentious issue in the state’s Democratic gubernatorial primary.

In that race, front-runner Ned Lamont, who had challenged Sen. Joe Lieberman from the left in 2006, argued that guaranteeing paid sick leave sent “the wrong signal out there at a time when we have a very high unemployment rate.” His opponent, Dan Malloy, favored paid sick leave and made the issue central to his campaign. Because of his position, Malloy closed a double-digit polling deficit and won the support of the Working Families Party, which helped propel him to victory. Lamont’s defeat sent a clear message that opposing paid sick leave came with a political cost, and Connecticut passed the first statewide law guaranteeing it in 2012.

In 2013, a nearly identical situation occurred in New York, where then-city council speaker Christine Quinn was the prohibitive favorite to be the city’s next mayor. For three years, Quinn blocked paid sick leave from getting a vote, despite supermajority support on the city council and an aggressive campaign led by the Working Families Party and prominent women leaders such as Gloria Steinem. As Quinn delayed, New York City Public Advocate Bill de Blasio spoke out, saying, “How on Earth has this bill not been brought to the floor? It’s not acceptable. It’s not democracy.” Shortly before Quinn lost the primary to de Blasio, Ginia Bellafante wrote about Quinn’s declining popularity in the New York Times, citing anger over “the incredibly long time it took her to support paid sick leave for privately employed workers.”

Following the high-profile battle in New York, the political calculus shifted. Eleven places approved paid sick leave requirements in 2014, including California, Massachusetts, and several cities in New Jersey. Oregon and Philadelphia joined them in 2015. President Obama further elevated the issue in this year’s State of the Union Address.

Today, the vast majority of Americans believe paid sick leave should be guaranteed, and Democratic presidential candidates Hillary Clinton, Sen. Bernie Sanders (Vt.), and former Maryland governor Martin O’Malley are lending their voices to the cause. But with more than 40 million Americans who still don’t get any paid time off, the fight is far from over. In April 2013, before New York’s paid sick leave bill passed, I wrote that America had “reached a tipping point.” During the past two years, we’ve seen a lot of encouraging progress. Just as important, we’ve seen how a grassroots movement can force an issue into the mainstream . And while too many working families are still ailing, we may finally have seen the beginning of the cure.

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