A collection of activists — from labor unions to immigrant rights groups — are planning protests across the country tomorrow to mark May Day.

Of course, the highest profile organization is Occupy Wall Street, which has called for a "general strike" and says events are planned in 135 U.S. cities.

Here's how the movement describes its plans on its website:

"Building on the international celebration of May Day, past General Strikes in U.S. cities like Seattle and Oakland, the recent May 1st Day Without An Immigrant demonstrations, the national general strikes in Spain this year, and the on-going student strike in Quebec, the Occupy Movement has called for 'A Day Without the 99%' on May 1st, 2012. This in and of itself is a tremendous victory. For the first time, workers, students, immigrants, and the unemployed from 135 U.S. cities will stand together for economic justice."

While it's unclear how big these protests will be, it is clear that this is a big test for the Occupy movement, which made headlines last year and is billing this protest as its spring renaissance.

Organizers told The Daily Beast that thousands and perhaps tens of thousands are expected in Manhattan, where the movement was born.

"If the protests end up being as large as organizers say, it would be Occupy's single largest demonstration since protesters were driven from their encampment at Zuccotti Park by the New York Police last November," The Daily Beast reports. "While smaller protests have continued through the winter and early spring, the day of action called for on May 1 is a bid to regain the national spotlight just as the presidential election campaign kicks into high gear — the question is whether in this heated environment, the Occupy movement can carry as much political weight as it did last fall."

CBS News reports that while there are lots of marches planned, there are also plans to disrupt traffic and public transportion. Authorities, reports CBS, are preparing accordingly.

It reports:

"In New York, the NYPD reportedly engaged in training exercises over the weekend, though officials aren't commenting on the details; NYPD Deputy Commissioner Paul J. Browne told CBS News that "[t]he NYPD accommodates lawful protest, and arrests those who break the law." In a number of cities, police are setting up barriers to control crowds and are receiving training on how best to deal with potentially aggressive protesters."Copyright 2016 NPR. To see more, visit http://www.npr.org/.