A movement that has no single message, no leader and no list of demands is nonetheless gaining steam across the U.S. with protesters from California to Maine expressing their anger with the U.S. economy and corporate greed.

The so-called Occupy Wall Street protests are now in their 18th day after an initial protest organized by Adbusters called on demonstrators to occupy New York's business district.

Since then, protesters ranging from students worried about their tuition loans, to union employees and laid off middle-aged workers have joined up.

In Manhattan they are camping out in a park near the New York Stock Exchange. On Monday, hundreds of protesters dressed up as money-hungry zombies, wandering past the NYSE clutching fistfuls of cash.

Rosie Gray, a reporter with New York's Village Voice newspaper, said the movement, which has sparked demonstrations in Boston, St. Louis, Kansas City, Mo. and L.A., appears to have struck a chord with many Americans.

The lack of a specific central message, she said, has allowed the group to remain inclusive to anyone with a beef against the government, economy, or corporate culture.

"Basically they're protesting the greed and corruption of our financial system and they're right to be frustrated but they don't have a single list of demands," Gray told CTV's Canada AM.

"The lack of message is not necessarily a bad thing because it allows them to connect with a lot of different groups. Basically they're just tapping into this anger at American society right now."

Though their message has remained broad, the group has become increasingly organized. Protesters at the New York City base camp are provided medical care, legal help and are even printing their own Occupied Wall Street Journal newspaper.

A focal point for the New york protest came Sept. 24, when about 100 demonstrators were arrested. The arrests, combined with reports of three women being pepper-sprayed resulted in a spike in media coverage as well as an increase in the total number of protesters.

Then on Saturday police arrested about 700 people for disorderly conduct and blocking a public street as they tried to march over the Brooklyn Bridge.

New York Police Department officers even commandeered city buses and forced drivers to drive across the Brooklyn Bridge while officers rounded up protesters. The drivers sued the NYPD on Monday as a result.

"We're down with these protesters. We support the notion that rich folk are not paying their fair share," said Transport Workers Union President John Samuelsen. "Our bus operators are not going to be pressed into service to arrest protesters anywhere."

Five more protesters were picked up by police on Monday.

"At this point, we don't anticipate wider unrest," said Tim Flannelly, an FBI spokesman in New York. "But should it occur, the city, including the NYPD and the FBI, will deploy any and all resources necessary to control any developments."

Flannelly said he does not expect the New York protests to develop into the often-violent demonstrations that have rocked cities in the United Kingdom since the summer. But he said the FBI is "monitoring the situation and will respond accordingly."

Some protesters compared themselves to a left-wing version of the Tea Party movement or a U.S. version of the 'Arab Spring,' which resulted in major political upheaval across the Middle East.

"We feel the power in Washington has actually been compromised by Wall Street," said Jason Counts, a computer systems analyst and one of about three dozen protesters in St. Louis. "We want a voice, and our voice has slowly been degraded over time."

With files from The Associated Press