By Jill McGivering BBC News, Washington

Many states have laws against sleeping in public

But it also has a large and growing problem of homelessness. It is estimated that about 1% of the population experiences homelessness in any given year.

Charities criticise the government for failing to do enough to help - and say US laws make the plight of the homeless even worse than it need be.

A US city with one of the worst records on homelessness is the US capital, Washington DC.

Porridge and bagels

It's just six o'clock in the morning in downtown Washington, still dark outside and bitterly cold.

DC having little affordable housing, a lack of social services and high poverty rate, it's kind of the perfect storm Scott Schingleberg, director of Miriam's Kitchen

But about 200 homeless people pour into a church hall - warm and brightly lit - to get hot breakfasts of porridge and bagels, and eggs and hot coffee.

Miriam's Kitchen, a charity, has been dishing out free breakfasts every day here for the last 21 years.

According to the charity's director, Scott Schingleberg, a number of factors contribute to the problem of homelessness in Washington DC.

"DC having little affordable housing, a lack of social services and high poverty rate, it's kind of the perfect storm, and that's why DC has one of the highest per capita rates of homelessness in the country," he said.

"I think, as a society, until we wake up and say these are systemic issues that we can't address through volunteerism or individual donations, we're going to continue to see this problem."

Miriam's Kitchen has seen an increase in demand of about 30% in the last few years.

Some of those it helps are chronically homeless, suffering from long-term mental or physical illness.

But actually they're the minority.

Homeless people are a common sight on New York's Fifth Avenue

Most people become homeless because of an economic crisis - like losing a job or being evicted or because their incomes just can't keep pace with rising housing costs.

"Once you lose housing, it's expensive to get back in - deposits, two months rent, have a bad tenant's history - so the threshold becomes much higher," says Nan Roman, president of the National Alliance to End Homelessness.

"So it's better to help people stay in the housing they've got."

The US is criticised for criminalising homelessness. Many states have laws against sleeping in public.

The homeless risk harassment from the police, even imprisonment.

Terry Snee now stays in a shelter for the homeless but until recently slept rough at Washington's Union Station.

"I've been a person that has lived on the street, more specifically at Union Station and people would just kind of wish that I wasn't there," Terry says.

"The police did harrass me. I was probably in the wrong place at the wrong time but the police were constantly asking me to move on."

No toilets

It's evening now, dark outside, raining a little bit and bitterly cold.

At the moment I'm in Georgetown, one of the most fashionable parts of Washington, full of restaurants and expensive shops.

Most shelters in DC are not open during the day and there's no place for people to go to the bathroom Susan Keenan, executive director of St Luke's shelter

But the area I'm heading to is just five minutes north of here - and has a very different feel.

This is a small basement kitchen in the church of St Luke's just north of Georgetown.

It's part of a different sort of shelter with just six residents who stay for an average of about six months. And every evening they sit down together to eat here. The food is prepared by volunteers.

Susan Keenan is the executive director here. She says the number of beds available to the homeless is woefully inadequate.

And the homeless are excluded from basic public services the rest of us take for granted - like access to toilets.

"Most shelters in DC are not open during the day and there's no place for people to go to the bathroom," she said.

"That's something you and I don't think about but what would you do if every place you went to said customers only? It's a really basic yet imperative need," she added.

Social stigma

There's no shortage of practical problems. But when I asked homeless people what they found most difficult, most spoke about the social stigma, the public attitudes toward them.

"Most people are so involved in their own daily lives, they look at you and if they sense you're homeless, you're kind of invisible to them," says Chester, who has been homeless for about two years.

"They're not bad, they're just that way. They look at you and they see you maybe, but they don't see you."

In the winter months, as the temperature falls below zero, a homeless person's struggle becomes all the more intense.