One thing is that this is going on in cities large and small.Many of the homeless individuals who served in some capacity in the U.S. military and for one reason or another they have broken down. This number is about 15% of the entire homeless nation. 1/3 of the meless nation is people with untreated drug and alcohol addictions or related problems that grow with little foodstuffs. Another 1/3 are related to economic exploitation such as labor pools that use men who have a marginal existence. The final 1/3 is untreated mental disturbances that normally need a stay in a hospital and follow uo visits to a clinic every 3 months while brain chemistry is improved and calibrated.

These figures overlap somewhat and come from E. Fuller Torrey who has written an astounding book named Nowhere to Go:
The Tragic Odyssey of the Homeless Mentally Ill.In this text he describes the millions of dollars slashed from the national budget by people working under Reagan in the National Institute for Mental Health. Also a factor is the policy of state government to close down dozens of state mental hospital paid by taxpayers because of better medicines that often allow patients a rounder life with employment, living on their own and dating.