“Labor is up against the wall, and they are looking for means of fighting back,” says Jackie DiSalvo, a 68-year-old union member and activist in Occupy Wall Street’s labor outreach working group, which organized Wednesday’s march of 20,000 people including members from at least a dozen unions in New York.

According to DiSalvo, “[The march] was a big breakthrough in that the unions were working together and they were supporting a very militant action—an occupation—and they were supporting an action which targeted the top one percent as the enemy, not just their own particular employers.”

Solidifying widespread union support (the AFL-CIO announced its support Wednesday) marks a significant step forward for Occupy Wall Street, not just in the large numbers of people that unions mobilize but also the diversity of people identifying with their struggle.

“Involving labor changes the racial composition of the group, because the workers in New York City tend to be black and Latino,” says DiSalvo, “And there’s also outreach being done by blacks and Latinos inOccupy Wall Street to communities of color, so we expect that as well as the labor alliance—and they overlap—to greatly strengthen the actions.”

Occupy Wall Street’s alliance with unions and other community organizations is not spontaneous. The labor support/outreach working group formed early in the occupation and has grown to more than 60 people. They have garnered support from unions by directly supporting labor struggles throughout the city. The effort began with Occupy Wall Street participants infiltrating and disrupting a Sotheby’s auction to point out that the company is making huge profits and increasing the CEO’s salary while expecting art handlers—Teamsters Local 814 members—to reduce work hours and drop their 401K plans.

Occupy Wall Street demonstrators next showed support for labor at a postal workers’ rally on September 27. Ari Cohen, a 21-year-old violin player who’s been camping out in Zuccotti Park since day one, described his participation:“The police actively tried to stop us—tried to kettle us, did block streets—but we still managed to outmaneuver them, to make turns around them to get to the postal workers’ rally, and when we got there, there was an outpouring of support, and it was such a powerful feeling.”

It was then, according to DiSalvo, that other unions saw how Occupy Wall Street could support them and the connections between struggles really started rolling. “ [The youth participants are] working class or they’re downwardly mobile from the middle class, so they have a natural alliance with the working class that are in unions,” she says. “I don’t think there’s been a youth movement that has so solidly taken up the agenda of labor and identified the enemy as the bosses that employ them.”

The positive energy emerging from such acts of solidarity offers the chance to answer a question most news outlets haven’t been asking about Occupy Wall Street participants—why do they stay? We know who they are—the 99 percent of Americans who don’t control most the country’s wealth—and we know that they’ve surged to Wall Street in the days since September 17 because they are fed up with the economic system we live under. But what makes hundreds of people remain in Liberty Plaza, facing mass arrests and sleeping outside even as the cold sets in and rain falls at night?

Some analysts point out that the participants’—especially youth—have nothing left to lose. While anger and frustration may be enough to bring people to the streets, it’s not the force that keeps them there. Put simply, these economic discontents are occupying Wall Street in order to build. What they’re constructing doesn’t come with blue prints, though. It’s a process that continues to unfold even as their energy sparks other occupations throughout the country.

“This space to me is almost like a brainstorming space,” says Sandra Nurse, a 27-year-old graduate student who has worked for the United Nations. “It’s a space where we can come together and have continuity in our ideas and in our conversations and think about how we can build a better world.”

Ari Cohen considers the participatory democracy happening in the space an active part of the building process. He says,“By attending these General Assemblies, places where everyone has a voice, where everyone is equal, there are no leaders, we are all horizontally organized, we are actually able to hear from people from different backgrounds, learn from each other, and through that process, not just in physical actions, but in intellectual and spiritual ways, learn how to create a new world, because we have so much to unlearn and this process itself, provides a way to begin to re-learn how we can interact with each other and how we can live with each other.”

Malcolm, a self-described cynic from Brooklyn who appreciates the social relationships at Occupy Wall Street, says, “I’m a big fan of example. If things are visibly existing outside of—as opposed to within—current systems of economy or politics, then people can see that and learn about it.”

The learning taking place in Liberty Plaza distinguishes the occupation from other forms of political action. By being there day and night, participants open themselves to questions and involvement from people who might not come out to an individual protest or march. “We’re right on Broadway. People are holding up signs and we have a welcome desk there, and passersby are coming and checking us out,” DiSalvo explains. “They’ll stay and listen to a speaker or come to a General Assembly. We’ll feed anybody who comes into the park.”

Besides being accessible, the taking of the park as a continuous public forum also signifies the resolve to make the education and discussions productive. Nurse says, “It is not a one-off event. This is a very serious effort to stay, and to say that we need to come up with something that’s going to be sustainable.”

Nurse knows there’s no easy solution. “As it stands I don’t see this as a model for necessarily a better world,” she says, “but it is a springboard for ideas, and I think that pushing, working through the pains of growing and expanding and incorporating the entire spectrum of voices and grievances is definitely something that is worthwhile.”

By securing solidarity from union workers, the spectrum of voices supporting Occupy Wall Street expanded tremendously this week. What’s next is for the participants to find new ways to draw out the rest of the 99 percent.