Most of Megan's bedroom is filled with the paraphernalia of a typical teenage girl -- piles of T-shirts, posters of her favorite stars, some stuffed animals she hasn't quite outgrown.
But then she goes to her closet and digs out a pair of sky-high silver stilettos. They are a glimpse into another kind of life -- the memory of which haunts her.
"I made my pimp about over $30,000 and I got nothing out of it," said Megan, who is just 17. "The most I've gotten is a pair of heels."
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Those shoes are a painful reminder of how she was coerced into selling her body for sex by an older man she hoped would become her boyfriend. Instead, she worked long hours in hotel rooms where she would service up to 20 men a night.
Megan's pimp did not make her walk the streets, she said. Instead, he advertised her online in the adult services section of the nationwide classified website, Backpage.com.
"My first ad, I had no idea what it said. I had no idea what they put on it. All I know is that they put the pictures that I took on there, and people started calling me," she said.
It's a phenomenon that has become commonplace in the lucrative and illegal commercial sex trade of minors: using the Internet as an instrument to facilitate business.
"It's safer than walking a track," Megan said, comparing the traditional approach with the newer cyber market. "People say, like, a 12-year-old can do it."
Megan is one of the thousands of American teens who fall victim to commercial sexual exploitation every year. Although sex trafficking is a major problem in the developing world, the U.S. Department of Justice estimates more than 250,000 youth are at risk domestically, and studies indicate the Internet could be making the problem worse by increasing demand. According to Shared Hope International, an anti-trafficking organization, the average age of entry for female prostitution is 13 years old.
And while there may be consensus that the exploitation of underage girls online is a problem, there is a white-hot debate over how to stop it. At the center of the storm is Backpage.com, which hosts an estimated 70 percent of the web's online prostitution ads. Critics say it's also a hub for the sex trafficking of minors, and have been mounting a public campaign to pressure Backpage to shut down its adult services section.
Despite Backpage screening their ads to look for minors, police around the country told "Nightline" they routinely find underage girls advertised on the website. But, the company argues, while Backpage might be part of the problem, it can also be part of the solution, by working with law enforcement to catch the pimps who are selling minors.
"I think it's very important to understand that to stop human trafficking online, you have to fight human trafficking online. And we provide an extraordinary tool to do that, because we are online," said Liz McDougall, the lawyer for Backpage.
McDougall has made this case before. In 2010, she was part of the legal team that defended Craigslist when it came under fire for its adult ads. Craigslist eventually decided to shut down that portion of its site, at which point much of that traffic moved to Backpage.
"I don't believe Craigslist did the right thing," she said. "And it would be the wrong thing for Backpage to take down its adult category. Because you are losing a key tool for law enforcement to get insights into this illicit activity, to get data, greater data than it's ever existed before, to locate, to identify the perpetrators, and to rescue victims."
Backpage makes money off these ads -- more than $20 million a year, according to AIM Group, an industry analysis firm. Backpage disputes that figure, but despite repeated requests from "Nightline," refused to provide numbers for how many escort ads get posted or how much revenue the company takes in from them.
"When there's this much money at stake, we think over $22 million a year, it's very easy to rationalize doing the wrong thing, to try to pretend that you're part of the solution when you're a problem," said Rob McKenna, the Washington state attorney general.
McKenna, a Republican who is also the head of the National Association of Attorneys General, has been leading the political charge to shut down the sex ads on Backpage.
"The idea that Backpage is somehow an ally of law enforcement is complete nonsense," he said. "They're actually allies of the pimps, of the traffickers. They're making it easy for men who exploit girls and women to get away with it."
But McDougall said what happened in the wake of Craigslist shutting down its prostitution ads is evidence that McKenna's strategy won't work. "Playing whack-a-mole, taking down an adult category from Craigslist and from Backpage, that is not the answer," she said.
McDougall is new on the job as Backpage's in-house counsel, a role she said she accepted only on the condition that she would be given free rein to address the problem of sex trafficking on the website.
"I've been on the job less than six weeks," she said. "Give me a chance and we are not going to lose this fight. I would love to see us eradicate sexual exploitation in the United States. I don't know if that's an achievable goal. But eradicating it online, I think is an achievable goal. And that's what I intend to lead the industry in doing."
Anti-trafficking advocates say both online classified and social networking sites have made ordering sex with a minor as easy as ordering a pizza. The cyber world provides johns with round-the-clock accessibility and provides pimps with an efficient, low-risk and anonymous method by which to recruit and sell women and children.
"[The Internet] can fuel the availability of prostitutes to a variety of individuals that wouldn't normally have it, or wouldn't normally go out to the street corner," said Sgt. Kyle Oki of the San Jose, Calif., Police Department's Human Trafficking Task Force.
"It's very easy for individuals to log onto the Internet, pull up Backpage or any variety of escort service sites, look at the picture, and call the number," he explained. "And as soon as you call it, you can make arrangements to meet with any girl you want."
Backpage is not the only website that sells classified escort ads; there are also Eros.com, CityVibe.com, Escorts.com, and MyRedbook.com, among others. But, according to AIM Group, when Craigslist famously shut down its escort ads in 2010 due to public pressure, Backpage quickly emerged as the market leader.
Backpage often points to the work of one scholar, danah boyd, of the Berkman Center for Internet and Society at Harvard University, who has written that the Internet provides new opportunities to intervene in the underground sex trade because it makes trafficking more visible than it once was.
McDougall lauded the systems Backpage already has in place to keep underage girls out of its adult ads.
"I think the company currently is better than anyone else out there. Our goal is to stay the industry leader, and to set the standard for everyone else to meet," she pledged.
McDougall took "Nightline" inside one of their screening rooms, the first time they have ever let reporters see how their filters function. According to McDougall, first an automated system screens for key words. Then, a real human being looks at each and every ad that goes up in the site's adult services section.
"Nightline" saw dozens of people at work, and Backpage says there are screening rooms in other locations, where in total, 80 percent of their employees are devoted to this kind of work.
Of course pimps and the underage girls they traffic often find ways to work around the safeguards, including using pre-paid gift cards instead of credit cards linked to an address.
"We're trying to stay ahead of them," McDougall said. "It's a cat and mouse game."
Backpage does work with law enforcement, responding to subpoenas and reporting about 400 ads a month to the National Center for Missing and Exploited Children.
Law enforcement officials from across the country told "Nightline" that they'd rather work with Backpage than be at odds with them. But many said the inescapable fact is that Backpage and other sites like it have made the buying and selling of sex exponentially easier than it was in the pre-Internet era.
"Before, you had to drive down the street. You had to build up the courage to make contact with someone. You had to stop out in public view," Oki said. "Now you're behind closed doors looking on your computer."
And he objects to the profits that Backpage and other sites like it are making off prostitution ads.
"I think it's wrong for any business or any Internet site to be profiting from the exploitation of women or children in the commercial sex industry," he said.
But Oki said he has mixed emotions on what the solution should be, noting that when Craigslist shut down its classified sex ads, the traffic moved to other sites.
"I'm kind of in the middle where the fact of, do I want to see these websites shut down, or remain open," he said.
Like many exploited minors, Megan had a troubled childhood fraught with family dysfunction and a sense of abandonment. She said she spent her early years searching for a father figure, as she bounced from relative to relative trying to find a stable home.
"I was used to getting kicked out. I was used to being, like, the troubled child," she said with tears in her eyes.
It all made her an easy and vulnerable target for the pimp who first approached her after she had spent the night sleeping at a bus stop.
"My first night, he took me to a hotel," she said. "And there was another girl there. And so, you know, he was like, 'Take a shower. Get ready and stuff. And we can take some pictures of you.'"
Megan said her pimp posted the provocative photos on Backpage.com. She had never heard of the site before and did not know how to use it, but after two months, she said, she started posting the ads for herself.
"I learned how to like, write the captions, I learned how to take the pictures," she explained. "I learned how to pay for the ad and everything, and it turned to be very, very simple."
"Nightline" obtained several of Megan's old ads, where she was listed as 19 and photographed in lingerie. Megan said the ads were typically posted three times a day; they cost $10 each and she said payment was made with an untraceable pre-paid Visa gift card that she purchased at the grocery store.
Megan said once an ad went up, the phone rang off the hook. She'd perform up to 20 or more tricks a night.
"It got to the point where I would act like I didn't hear my phone ringing because I was so exhausted," she said. "I was so-- I didn't want to do it anymore. I was in pain and I would just act like I didn't hear my phone ringing."
Megan said she was bringing in up to $4,000 a night, but wasn't allowed to keep a penny of it. If she wanted something to eat, she had to ask her pimp for permission. Then one day, he kicked Megan out, leaving her on the street in only a trench coat and no shoes. Her family rejected her calls for help and eventually the police picked her up.
"Megan's story is very typical of many girls," said Lea Benson, who heads the safe house run by StreetlightUSA, where Megan was in recovery. "When a girl is booked, we get a call immediately from either FBI or the vice [squad] that says, 'We've got a girl, are you guys ready to take her?'"
StreetlightUSA, which is funded primarily by area churches, is one of the few facilities in the country where girls who have been sold for sex, ages 11 to 17, can come for rehabilitation. In addition to food and shelter, the girls at StreetlightUSA receive counseling, mentorship, schooling and recreational activities like art classes and yoga.
But in most cities recovery centers like StreetlightUSA just don't exist, and most girls end up in juvenile detention facilities.
Benson said that more than 50 percent of the girls at Streetlight had been trafficked on Backpage.
"What words could explain the horrific outcomes that are a result of the girls being advertised on these sites?" she asked.
She acknowledged that rehabilitation of trafficked teens is extremely challenging, and it's not infrequent that girls run away.
"Trust is an issue for the first 20 to 90 days," she said. The center struggles with funding, but, she said, they never refuse to take in a new girl.
"They come with so much trauma that the healing will be a lifetime," Benson said. "Our goal here at StreetlightUSA is to help them write a new story."
Recovery, though, is possible. Jessica, now 23, said she was also pimped on Backpage when she was underage. She described horrific physical and emotional abuse she endured under at the hands of a pimp when she was just 16.
"Every pimp has a series of rules that each girl is required to follow," she said. "There was a time where I didn't obey the rules. My pimp decided to take a potato peeler... He came, grabbed me by my throat, held me against the wall, took the potato peeler, carved it into my face.
"[He] then ate the skin and told me I'm his forever and if I ever leave, worse things will happen to me," she said.
Jessica lives with the scar on her face, but has turned her experience into action, working with FAIR Girls, an advocacy group for victims of sex trafficking.
"If we could save one child, that one child could have been me," she said.
Her pimp is now behind bars, due in part to her testimony against him. Jessica now has her sights set on becoming a lawyer, and is working to shut down online marketplaces that allow for adult advertisements.
"If I could at least do that when I get out of law school, work and be an advocate for victims, I could make sure that I could get rid of places like Backpage's adult section so that children are not forcibly sold every day," she said.
Washington Attorney General Rob McKenna said Village Voice Media, which owns Backpage and dozens of alternative newspapers around the country, including the venerable New York City publication, The Village Voice, has a moral obligation to shut down the ads.
"With Backpage being such a high profile company, they're normalizing this practice of advertising prostitution online," McKenna said. "They're essentially sending a signal 'hey this is OK, there's nothing really wrong with this,' when in fact it's resulting in the massive victimization of women and girls across our country. Will it move? It might well. But we can't allow this open casbah -- this market place to exist in such a high profile fashion because it encourages others to do even more of it."
McKenna and other attorneys general are somewhat bound by a law Congress passed in 1996 called the Communications Decency Act. The Act says that Internet service providers or "interactive computer services" like Backpage are merely hosts and not publishers in the traditional sense.
That means that the websites cannot be held liable for material posted on them by a third party, which is why, while the act of prostitution may be illegal, Backpage is not responsible for someone posting an ad for it on their site.
"I've thought about whether there's a federal fix," said Backpage's lawyer Liz McDougall. "I have yet to be able to think of what would be a constitutionally sustainable amendment to that law that wouldn't, at the same time, devastate the Internet."
McKenna said some in Congress are exploring how the law might be changed. In the meantime, he pointed to a recently passed law in his home state of Washington that would require sites like Backpage to obtain documentation that the escorts in posted ads are over 18. McDougall said she expects that law to be challenged in court.
Watch "Nightline" anchor Cynthia McFadden's full report on "Nightline" TONIGHT at 11:35 p.m. ET/PT