A recent study, presented as the most comprehensive, found that about 4.2 million children and a young adult live without shelter in the United States.
Researchers at the University of Chicago applied a broad definition of homelessness, including people living in the open, or those in shelters, as well as people who temporarily resided in others because of their lack of permanent private housing.
"Our study aimed to give our nation the first time a fuller view of homeless youth by including young people who were always included" in previous studies, Matthew Morton said.
The study counted at least 700,000 adolescents between the ages of 13 and 17 without permanent shelter and 3.5 million young adults between the ages of 18 and 25.
Blacks and people of Latin American origin are particularly concerned about the problem, as well as homosexuals, the researchers said, noting that the results of their study would help the authorities approach the problem.
"We have a collective duty to make sure that all young people have a chance to succeed from a young age," said Brian Samuels of the University of Chicago.
"We can focus on missed opportunities at school, in neighborhoods and in public service agencies," Samuels was quoted as saying by AFP.
The study also found that the proportion of displaced youth was similar in urban and rural areas, even if they were less prevalent in rural areas.