In the 1980s a series of national and local studies were undertaken to enumerate homeless people. Although these studies had considerable methodological difficulties, they revealed the great variety of sites used by homeless people. Some classifications of homeless persons were proposed according to where homeless people spend their nights. For instance, based on field studies of samples throughout Ohio, Roth et al., (1985) classified homeless people as street people, shelter people, and resource people (the latter including people who doubled up with family or friends). Doubled-up people, the largest category by far, had not been studied before the 1980s. Further studies showed that they were a large source of “literal homelessness” (Weitzman, Knickman, and Shinn, 1990) and that there was considerable back and forth movement among these three groups.
The same cohort of 1980s studies also provided valuable information about the way people became homeless, yielding two main groups: the majority became homeless because they could not pay for their housing; a lesser number became homeless because they fled abusive environments (battered spouses, runaway youth) or were thrown away from their home by parents or partners. Finally, the same studies showed that many people were recurrently homeless and pointed to three groups of homeless persons: new (homeless for the first time), episodic (recurrent homelessness) and chronically homeless (continuously for more than a year [see, for instance, Ropers, 1988]).
A more recent contribution (Mackenzie and Chamberlain, 2003) introduces the concept of homelessness careers. It identifies homelessness as a career process for a series of transitional stages in the development of any form of biographical identity, (i.e., people passing through various phases before they acquire the identity of homeless persons). They distinguish three pathways: (1) the housing crisis career, with poverty, accumulating debt, unstable housing, and eviction preceding homelessness; (2) the family breakdown career, with abuse or violence associated frequently with return to an abusive home and recurrence of that process until a final break occurs; and (3) the youth homelessness career continuing into adulthood for people who have been homeless since their teens.
By focusing on people in homeless shelters in two cities and developing a city-wide information retrieval of administrative data from shelters, Dennis Culhane opened the way for very large and relatively accurate data collection projects. Kuhn and Culhane (1998) applied cluster analysis together with an information retrieval system to trace homeless persons through the shelters in Philadelphia and New York to produce three groups of homeless persons—transitionally, episodically, and chronically homeless—by number of shelter days and number of shelter episodes. Transitional, episodically, and chronically homeless constituted, respectively 80 percent, 10 percent and 10 percent of shelter users. However, the latter group consumed over 50 percent of shelter beds. These data were cited in congressional hearings that led to Federal appropriation of funds for initiatives to end chronic homelessness (U.S. Department of HUD, 2002 and 2004).
Kuhn and Culhane reported differences in racial origin, age, and physical and mental conditions among the three groups. However, they dealt with a selected population (shelter only and two cities). In studies of the users of a Toronto shelter, Goering and colleagues (2002) found little difference between transitional and episodic groups. In studies of chronically, episodic, and housed adults attending a detoxification program who were followed for 2 years, chronic homelessness was associated with poorer scores over time on a mental health instrument but not on a health-related quality of life instrument (Kertesz et al., 2005).