Every year as the cold weather arrives, the U.S. Conference of Mayors conducts a survey of who's living in homeless shelters. This year, it uncovered a troubling statistic: a 9 percent increase in the number of families who are homeless.

These numbers have been increasing - the Department of Housing and Urban Development notes a 30 percent growth since 2007 - and are expected to bump up again next year.

Many of these families, remarkably, continue to function, even as the basic need for shelter is threatened or removed entirely. Wendell Chu, the school superintendent in East Islip, says that more students are showing up for class with their homes facing foreclosure. Many more qualify for free and reduced-price lunch - another measure of families in distress.

"This creates stress for these kids," he says. "It affects how kids come to school, their readiness to learn."

As the country continues to pump billions of dollars into homeless programs, food stamps and other safety-net services, the very people these programs are meant to help - mothers and children - continue to struggle. While the welfare overhaul of the late 1990s was intended to create a path from welfare to work, its effect in the current troubled economy may well be simply dumping people without support.

The mayors were asked to identify the three main causes of homelessness among households with children. The top responses were unemployment (76 percent), lack of affordable housing (72 percent), poverty (56 percent), domestic violence (24 percent) and low-paying jobs (20 percent).

To be sure, we are living through a historic economic catastrophe, and this period will leave a mark on our national psyche. More Americans were poor in 2009 - 43.6 million total - than at any time since the U.S. Census Bureau began estimating the poverty rate 50 years ago. Jobless rates are also very high.

Our social safety net simply has too many holes. While some dismiss the homeless - depicting them as either too crazy, drugged or afraid of the authorities to seek help - surely we're not ready to concede that there's an acceptable level of homelessness for families.

The Long Island Coalition for the Homeless is preparing for its annual count of homeless people later this month. Last year, the group found 1,046 families in Suffolk County and 446 in Nassau living in emergency shelters or transitional housing.

Long Island wasn't part of the Conference of Mayors survey, but the coalition's Julee King says the trends hold true here. In the past 18 to 24 months, the coalition has fielded more calls from families, particularly those being evicted because the homes they're renting are being repossessed.

It's extraordinary that this is happening on well-to-do Long Island. Fortunately, we have a network of charities, religious and secular, that provides temporary housing. But it would be better to prevent homelessness in the first place. The dislocation is disruptive, as the school superintendent points out, and it's inhumane.

Boston is experimenting with banning evictions. Many cities, including Chicago, are expanding consumer credit counseling. Of those surveyed in the mayors' study, 92 percent said housing vouchers to reduce rents would be an effective remedy for homelessness, and 71 percent advocate higher wages for low-end jobs. Given economic realities, that's unlikely to happen any time soon.

Still, these are important ideas. Nobody, least of all children, should have to cope with so much insecurity when it comes to something as basic as shelter.

Originally published in Newsday