People with untreated serious mental illness comprise an estimated one-third of the total homeless population in the United States and an even higher percentage of women and individuals who are chronically homeless.

In major cities from New York to San Diego, homeless people with severe mental illness are now an accepted part of the urban landscape and make up a significant percentage of the homeless who ride subways all night, sleep on sidewalks and hang out in public facilities such as libraries and bus stations. Many others live hidden from the sight of fellow citizens, shuffling quietly through the streets by day, talking to their voices only when they think nobody is looking, living in shelters or abandoned buildings at night. Some who are psychiatrically ill live in the woods on the outskirts of cities, under bridges, and even in the tunnels that carry subway trains beneath cities. In places, homelessness shelters are so populated by mentally ill wanderers they take on the appearance of hospital psychiatric wards.The quality of life for these individuals is abysmal. Their mortality rate is 4 to 9 times higher than the general population. Many are victimized regularly. They are highly likely to be arrested at some point and then cycle from the streets through the jails.

Treatment Advocacy Center
September 2016
http://www.treatmentadvocacycenter.org/evidence-and-research/learn-more-about/3629-serious-mental-illness-and-homelessness

Serious Mental Illness and Homelessness: Background Paper – 2016-09