DALLAS (AP) — From barbecues to outings to shopping for sales, many people in the U.S. are celebrating Labor Day, the federal holiday honoring the American worker, by finding ways to relax.

This year marks the 130th anniversary of the holiday, which is celebrated on the first Monday in September. Although union action in recent years to stand up for workers has been a reminder of the holiday’s activist roots, The resulting three-day weekend has become a milestone in the lives of Americans celebrating the unofficial end of summer.

Here’s what you need to know about Labor Day:

How Did Labor Day Become a Federal Holiday?

Its origins date back to the late 19th century, when activists first sought to establish a day to pay tribute to workers.

The first celebration of Labor Day in the United States took place in New York City on September 5, 1882, when some 10,000 workers marched in a parade organized by the Central Labor Union and the Knights of Labor.

Workers saw their quality of life decline as they moved from craftsman to factory work, while factory owners’ quality of life “just skyrocketed,” said Todd Vachon, an assistant professor at the Rutgers School of Management and Labor Relations.

In the years that followed, a handful of cities and states began to pass laws recognizing Labor Day. President Grover Cleveland signed an act of Congress in 1894 making it a federal holiday.

That was the same year that workers at the Pullman Palace Car Company went on strike after the rail car manufacturer cut wages without reducing rent in the company-owned city where the workers lived near Chicago, Vachon said. More than a dozen workers were killed after Cleveland sent federal troops to quell the strike, he said.

According to Vachon, Cleveland’s decision to declare Labor Day a federal holiday is seen by some historians as a way to “make peace” with the working class.

What do Americans do during Labor Day weekend?

During the three-day weekend that Labor Day ushers in, travelers flock to airports and highways to wrap up summer and chefs prepare barbecues for family and friends.

According to Robert F. Moss, food writer, culinary historian and author of “Barbecue: The History of an American Institution,” barbecuing has been a part of Labor Day celebrations since the beginning.

He said it was such a deep-rooted tradition in the U.S. that when labor movements developed in the late 19th century, it was natural to celebrate when large groups gathered. In the 20th century, the holiday’s barbecues shifted more to gatherings of friends and family in backyards, he said.

“There’s still a lot of that same sense of community, gathering around the grill and eating together,” he said.

According to Vachon, whether someone reflects on the origins of the labor movement during the commemoration depends on whether he or she lives in a place with a lot of unions.

In Chicago, a parade and festival are held over Labor Day weekend in what is now the Pullman neighborhood, home to the holiday’s roots. Bob Reiter, president of the Chicago Federation of Labor, said the parade and festival they organize draw union members and their families from across the region.

How has the labor movement developed over the decades?

When Labor Day became a federal holiday in 1894, unions in the U.S. were largely contested and courts often declared strikes illegal, leading to violent conflict, Vachon said. It wasn’t until the National Labor Relations Act of 1935 that private-sector workers were given the right to unionize.

Later in the 20th century, states also began to pass legislation to allow unionization in the public sector. Even today, however, not all states allow collective bargaining for public employees.

According to Vachon, there has been a revival in union organizing, activism, interest and support in recent years.

“A lot of millennials and Gen Z people are entering the workforce at a time that’s not all that different from the 1880s, when there was a lot of turmoil in the labor market,” Vachon said. “Jobs just aren’t paying enough to fulfill the American dream.”

What is the connection between fashion and Labor Day?

The saying that you can’t wear white after Labor Day is a “rule” that broken with very fashionable resultsbut where does it come from?

Fashion experts say it likely dates back to the Gilded Age — the same period in the late 19th century that gave birth to Labor Day. The cool, white dresses that wealthy New Yorkers wore during their summers in places like Newport, Rhode Island, would be put away when they returned to the city’s dirty streets at the end of the summer.

Christy Crutsinger, a professor of merchandising and digital retailing at the University of North Texas, has heard the saying from generations of women in her family. But “the fashion world doesn’t work that way anymore,” she added.

“People think it, say it, but don’t follow through,” she said.

With back-to-school preparations underway and many businesspeople transitioning from a more relaxed summer dress code, fashion is taking center stage for many this Labor Day, says Daniel James Cole, associate professor of fashion history at the Fashion Institute of Technology and co-author of “The History of Modern Fashion.”

The vacation, he said, “is kind of a pivot point” between summer clothes and fun and “getting back to more serious pursuits.”

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Associated Press reporter Wyatte Grantham-Philips contributed to this report.