While the Democratic National Convention is underway in Philadelphia, a coalition of social service organizations is standing by in case sex-trafficking victims need help, whether it's a ride or a safe place to sleep.

Typically, big events with big crowds translate to more instances of trafficking. The city expects up to 50,000 visitors during the convention, which ends late Thursday night.

"Typically, there's a shame. That's the No. 1 preventer of human trafficking. People are afraid of being caught. So if you're in an unknown area, you're more willing to take the risk," said Hugh Organ, associate executive director of Covenant House Pennsylvania.

That organization is spearheading the DNC Human Trafficking Collaborative. Groups such as The Salvation Army and Dawn's Place are also members.

In the weeks leading up to the convention, the coalition visited 61 hotels in the city to train employees how to spot sex trafficking, especially involving girls and boys under 18.

"You're looking for people who are checking in without any luggage, who offer to pay in cash and not credit cards because anything that creates a paper trail, traffickers are going to stay away from, then they ask for specific requests, like they only want rooms on the first floor near the exit," said Organ.

Guests who decline housecleaning for days on end can also be seen as suspicious.

If law enforcement identifies victims of sex trafficking, organizations such as Covenant House can provide a room at its 51-bed facility in Germantown, among other resources.

Representatives of the coalition will be on hand all week at the Pennsylvania Convention Center to educate people about sex trafficking.

To report suspected trafficking, call the National Human Trafficking Resource Center hotline at 1-888-373-7888.