Cities across the United States have spent at least $13 million in response to the Occupy Wall Street movement on police overtime and other services, according to a survey by The Associated Press.

Authorities say the police spending is for the public's safety, while protesters say cities could save money by simply letting the demonstrations against economic inequality and corporate greed continue.

Cities that have seen the most clashes between Occupy protesters and police, including the movement's original site in New York City, have spent the most on police work.

The AP gathered figures from government agencies in 18 cities with active protests and focused on costs through Nov. 15, the day protesters were evicted from New York's Zuccotti Park, where the protests began Sept. 17 before spreading nationwide. The survey provides a glimpse of spending by cities large and small.

Broken down city by city, the numbers are more or less in line with the cost of policing major public events and emergencies. In Los Angeles, for example, the Michael Jackson memorial concert cost the city $1.4 million.

The spending comes as police departments across the U.S. have cut overtime budgets, travel and training to respond to the recession. Nonetheless, city officials say they have no choice but to bring in extra officers or hold officers past their shifts to handle gatherings and marches in a way that protects free speech rights and public safety.

In some cities, officials say the spending is eating into their overtime budgets and leaving less money for other public services.

Protesters blame excessive police presence for the high costs in some places.

"We're here fighting corporate greed and they're worried about a lawn?" said Clark Davis of Occupy Los Angeles, where the city estimates that property damage to a park, including destroyed sprinklers, has been $200,000. About 500 protesters' tents are jammed into the park surrounding City Hall.

In Oakland, California, where protesters have clashed more than once with police and temporarily forced the shutdown of a major port, the city has spent more than $2.4 million responding to the protests. The cash-strapped city already faced a $58 million budget gap this year.

"The cost of the encampments is growing and putting a strain on our already fragile resources -- police, public works, and other city staff," said Mayor Jean Quan.

In New York City, the police department has spent $7 million in overtime on the protests. But that's small change given the department's $4.5 billion budget, which allots money for emergency overtime. Last year, the New York Police Department spent about $550 million on overtime.

Pete Dutro, a protester in charge of finances in New York City, called the NYPD's response "completely unnecessary."

"It's $7 million of taxpayers' money that's being spent to stifle our First Amendment rights" to free speech and assembly, he said.

Other cities were not too concerned about mounting costs, with officials saying they budget for events like these.

"Our view is that unexpected things happen," said Sonji Jacobs, spokeswoman for Atlanta Mayor Kasim Reed. "Occupy Atlanta is something that folks didn't necessarily see coming, but the good news is that we have flexibility in our budget."

Overall, the city spent nearly $652,000 on the protests, paying for everything from overtime for police officers and firefighters to running its mobile command center. The city has $56 million in its reserve fund.

Costs were far lower in Boston than City Council President Stephen Murphy initially predicted last month, when he said police costs for providing security at Occupy Boston for October would be as high as $2 million. The city of Boston has spent $575,000 in overtime through mid-November to pay officers policing the protest. That's about 2 percent of this year's $30 million police overtime budget.

"We have a history of starting, as well as managing, historic demonstrations," said City Councilor Michael Ross. "We've done it well and we've managed it well, and that's not going to stop anytime soon, and that doesn't cease to exist after it hits a certain budget threshold."

Meanwhile, Occupy protesters in Portland, Oregon, on Wednesday promised some kind of surprise action on Friday, the day after Thanksgiving and the traditional start of the holiday shopping season in the U.S.

Some said they don't want people to shop at all. Others just want to divert shoppers from big chains and giant shopping malls to locally owned businesses. Although the actions don't appear coordinated, they have similar themes: supporting small businesses while criticizing the day's dedication to conspicuous consumption and the shopping frenzy that fuels big corporations.

In Seattle, protesters are carpooling to Wal-Mart stores to protest with other Occupy groups from around Washington state. Washington, D.C., is offering a "really, really free market," where people can donate items they don't want so others can go gift shopping for free.

Also on Wednesday, Occupy participants in New York said they are putting out a benefit album with music from Third Eye Blind, David Crosby and Graham Nash, Jackson Browne, Lucinda Williams, DJ Logic, Ladytron and others.

Jason Samel, a musician who is putting together the disc, says the goal is to raise between $1 million and $2 million to help fuel the movement that is protesting income disparity.

It will be available this winter, at first in digital form only.