There were 744,000 homeless people in the United States in 2005, according to the first national estimate in a decade. A little more than half were living in shelters, and nearly a quarter were chronically homeless, according to the report Wednesday by the National Alliance to End Homelessness, an advocacy group.

A majority of the homeless were single adults, but about 41 percent were in families, the report said.

The group compiled data collected by the