For two frightening weeks, 17-year-old George lived in a tree because, he said, he had nowhere else to go.
The teen thought he was going to stay with family in California. In August 2009, the woman he called "Mom" -- an aunt who had raised George since he was a baby -- bought him a Greyhound bus ticket from Missouri and gave him what she said was an address for relatives in San Francisco.
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But before he arrived, George said he received some shocking news: His aunt told him, over the phone, that the address she provided was not for relatives but for a McDonald's.
"My mom called me and told me that I didn't have any relatives in San Francisco and I was basically screwed," he said.
George's aunt denies this, telling "20/20" that George did, in fact, have relatives in San Francisco but that she did not know their names.
All of a sudden, George found himself homeless -- and he wasn't alone. There are nearly two million homeless youth in America. In San Francisco alone, social workers see some 6,000 cases of homeless teens a year.
Toby Eastman, a San Francisco social worker, sees many teens like George.
"We see a lot of young people that are just rejected from their family," she said.
For 14 months, "20/20" followed teens like George and watched how they struggled with problems no teenager should have to face.
There was Rebecca, who spent months couch-surfing with friends, including an older man, because she didn't get along with her mother's boyfriend.
There was Dakota, an honor student who fought for emancipation from her unreliable mother.
And there was June, who was biologically a boy but identified as a girl. He risked life on the streets to avoid bullying by his brothers at home.
Eastman says that teens like George who are rejected by their families face a trauma that results in a sort of emotional distance.
When we first met George, he said he didn't miss his family at all.
"If I think about them then I'll just bring back dumb memories I don't need to worry about," he said.
George arrived in San Francisco with $50 in his pocket. For his first two weeks there, he slept in a tree at a Golden Gate Park. It was safer, he said, than sleeping on the ground, where "a lot of people could tamper with you."
"The only bad thing that could happen in a tree is if you fell out," he said.
George washed himself with paper towels in public bathrooms and ate almost nothing to make his dollars last.
He tried calling his family but to no avail.
"I tried to call them twice and they didn't answer both times. Then I was like, 'What's the use?'" he said.
Exactly why he was sent away remains a mystery. George's aunt told "20/20" that he assaulted classmates, abused her children and was out of control. She said she had no choice but to get him away from her family at any cost.
George denied that. When "20/20" checked in with police, officials at schools George attended and his grandparents, it found no record of serious behavioral problems.
Eventually, without his family's help, George found a place to stay. At a library, he came upon the name of a shelter for teens run by Larkin Street Youth Services. He also reenrolled in school.
He kept trying to reach his aunt. One day last spring, days before his high school graduation, she answered the phone.
It was a halting conversation, full of long silences on her end. He told her about his upcoming graduation ceremony. He was hoping, he said, that she would tell him she wanted to come.
But George didn't celebrate his graduation alone. His friends at the shelter filled the void, throwing a surprise party in his honor.
Today, George is a freshman at a community college in San Francisco. He continues living in a shelter but has reconnected with some of his family -- his grandparents. He spent Christmas with them.
It was a time, he said, of "a lot of shopping, love, arms around me."
Not all the teens we followed have been as fortunate.