By Richard Allen Greene and Piers Wisbey
BBC News, Washington
Martin Walker was working for a law firm when he was injured in a car accident.
He had to take time off work for therapy, during which time, he says, he was fired.
Martin Walker became homeless after losing his job
"After I lost my job, I got behind on my bills and my rent. And that's how I became homeless," he says.
That was more than two years ago. Since then, he has held some regular jobs, and works between jobs as a vendor for Street Sense, a Washington DC newspaper designed to help the homeless.
But he has never managed to save enough to get himself a home. He spends most nights in shelters.
"Fortunately, I have had to sleep outside only a small number of times. Some people prefer it, but it's pretty dangerous sleeping outside," he says.
Victims of attack
Indeed, a new report from the National Coalition for the Homeless says that 2006 saw the largest number of attacks - by far - of any year since the group began keeping records in 1999.
Twenty people were killed in the 142 violent crimes against homeless people, the group found.
A separate US government study claiming to be the most comprehensive ever found that 704,000 Americans were without shelter for at least one night between February and April 2005.
Some 754,000 "are living in emergency shelter, transitional housing, and on the streets on any given night", the study found.
HOMELESSNESS IN AMERICA
Roughly 754,000 Americans are in a homeless shelter or on the streets on any given night
About a third are families with children
About a quarter are disabled
About half are black
That is roughly in line with earlier, smaller studies suggesting America's homeless numbered around 750,000 - about 0.25% of the total population.
Families with children made up one-third of the homeless people in the large study.
One in four was disabled. Nearly half were black - in a country where just over one in 10 people is black.
The Department of Housing and Urban Development, which carried out the study, counted only those actively seeking shelter, not people sleeping rough, so the total number of homeless Americans is almost certain to be higher.
And there is some dispute about the very definition of homelessness. As Street Sense itself reports, people staying with friends or family because they have no place of their own - "couch surfers" - do not figure in the homeless statistics.
Fighting the problem
Amidst all the statistics, measurements and reports, more than 100 local and state leaders met in Washington this week to discuss the problem.
Their sponsor, the US Interagency Council on Homelessness, says there is reason for optimism - more than 20 US cities are reporting that numbers of rough sleepers are declining.
"For the first time in 20 years, we are beginning to see a decrease in the numbers," the council's executive director Philip Mangano said on the eve of the summit.
The summit's keynote speaker said such a drop was long overdue.
Louise Casey, who led Britain's drive against homelessness, says the United States has finally realised something must be done.
"Where they are in the US is where we were around 1997, 1998, when the government said: 'Enough is enough,'" she said, referring to the period when she became the UK "homeless tsar".
She was pleased to hear many of the mayors at the conference sign up to "10-Year Plans" to reduce homelessness, she says.
"But what I have been saying is: 'Don't wait 10 years, do it now.'"
Laura Thompson Osuri, the executive director of Street Sense, says cities need to do more than create plans - they need to fund them.
Washington, she says, has a plan but has not put it into action - although it is seeing a rise rather than a fall in the number of homeless people.
She worries that not enough attention is being paid to the problem.
"People have become so used to seeing homeless people on the street that it's not shocking any more. It's become accepted," she says.
"Attitudes need to change. We need to shock people. This is a big problem and something needs to be done about it."