With a million party-minded football fans flocking to Minneapolis for the Super Bowl - dubbed the biggest trafficking event in the US - dozens of agencies are gearing up to bust criminal networks and rescue victims.

Minneapolis police says it is working with 23 law enforcement agencies, patrolling the web to target people buying sex online and monitoring hotels for sex trafficking.

While the anti-slavery group Polaris will be staffing up its anti-trafficking hotline, its chief executive Bradley Myles cautioned against painting the country's largest sporting event as a sex trafficking magnet.

"All this is, is a one-day snapshot into what otherwise is a 365-day problem," he told the Thomson Reuters Foundation.

"The same traffickers that are committing trafficking... during the Super Bowl, they're going to wake up in the morning on Monday and do the same thing."

There is a darker side to the biggest game in the US sporting calendar (
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USA Today Sports)

Big sporting events, from the World Cup to the Olympics, regularly trigger a panic over an influx of sex-trade workers , with many being victims of human trafficking.

Arrests of pimps running underage sex rings are reported at the National Football League's championship game almost every year, with girls being trafficking from as far away as Hawaii to hook up with clients via the Internet, hotels and strip clubs.

Some 1.5 million people in the United States are victims of trafficking, mostly for sexual exploitation. The majority are children, according to a US Senate report published last year.

US police arrested about 750 people in nationwide sex-trafficking sting operations ahead of last year's Super Bowl, the largest sweep since operations began 13 years earlier.

The Super Bowl is potentially the biggest sex trafficking magnet in the US (
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Getty Images Europe)

Although the attorney general of Texas dubbed the Super Bowl the "single largest human trafficking incident" in the United States in 2011, this is largely a myth, academics and anti-trafficking campaigners said.

The commercial sex market grows modestly during Super Bowls, but also during other large events, from the Las Vegas consumer electronics show to Memorial Day weekend, said Lauren Martin, a trafficking expert at the University of Minnesota.

After reviewing 55 academic papers and more than 100 media stories about prostitution and the Super Bowl, Martin says research points to a likely spike in sex trafficking because 5 to 20 percent of sex workers are trafficking victims.

"But after the event is over, the levels of activity in the commercial sex market will go back to what they were," she said, adding more research is needed as it is a relatively new field.

With a million party-minded football fans flocking to Minneapolis for the Super Bowl dozens of agencies are gearing up to bust criminal networks and rescue victims (
Image:
USA Today Sports)

Artur Dubrawski found online escort ads proliferated when US cities hosted large public events in his regularly-cited 2016 study, but recognises some have criticised his approach.

"Certain researchers question the validity of using web advertisement" to size up a city's commercial sex market, the Carnegie Mellon University computer scientist said.

The Global Alliance Against Traffic in Women (GAATW) is among the most vocal critics of those who link the Super Bowl with a spike in trafficking, dismissing it as "manufactured media hype" that seeks to raise funds and attract attention.

This is damaging, says the coalition of nonprofits, which campaigns for the rights of sex workers, migrants and domestic workers, as well as trafficking survivors.

"What is the cost of such rumors?" asked Annalee Lepp, an expert in human trafficking at Canada's University of Victoria and GAATW board member.

"There are really harmful effects ... on the very people that everybody is so concerned about."

Big sporting events such as the Super Bowl regularly trigger a panic over an influx of sex-trade workers, with many being victims of human trafficking (
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REX/Shutterstock)

GAATW says the "moral panic" over sex trafficking at sporting events wastes resources that are needed elsewhere and increases criminal penalties against sex workers who are displaced in city 'clean up' efforts.

Campaigners are hopeful that officials are starting to recognise trafficking as a complex, long-term problem.

"We know sex trafficking occurs, it occurs every day," the City Attorney of Minneapolis, Susan Segal, said at a public briefing of lawmakers about the sporting mega event in January.

"It's going to occur well after the Super Bowl has come and gone."

This impressed Michelle Guelbart of campaign group ECPAT-USA, who helps businesses stop child sex trafficking.

"The conversation is moving in the direction that we want it to," she said.