More than 500,000 people — a quarter of them children — were homeless in the United States this year amid scarce affordable housing across much of the nation, according to a study released Thursday.

The report, from the U.S. Department of Housing and Urban Development (HUD), said the number was down slightly from 2014. Many U.S. cities are confronting a sluggish economic recovery, stagnant or falling wages among the lowest-income earners and budget constraints for social welfare programs.

Los Angeles, Seattle, Portland, Oregon and Hawaii have all recently declared emergencies over the rise of homelessness, and on Thursday, Seattle's mayor toured a new encampment for his city's dispossessed.