The Annual Homeless Assessment Report (AHAR) is a HUD report to the U.S. Congress that provides nationwide estimates of homelessness, including information about the demographic characteristics of homeless persons, service use patterns, and the capacity to house homeless persons.
The report is based primarily on Homeless Management Information Systems (HMIS) data about persons who experience homelessness during a 12-month period.
Source : https://www.hudexchange.info/hdx/guides/ahar/