Many people see a homeless person on the streets, and they think that such a situation could never happen to them. Recently, PBS chronicled vital statistics databases and homeless shelters all across the U.S. to determine the biggest causes of homelessness.

Lack of adequate health care is right at the top of the list. 1/3 of Americans have no health insurance, and most of these are low-income workers. The sicker they become, the more likely they are to be laid off. Without health care, they cannot get better. If they cannot get better, they cannot work. As a result, they end up homeless and the vicious cycle continues.

Domestic violence is another major factor of homelessness, especially in women. This goes hand in hand with mental illness, which can spur domestic violence and victim abuse. Since many hospitals were closed in the 1980s to de-institutionalize the mental health industry, patients have become homeless.

Finally, substance abuse is another major cause of homelessness. Even Hollywood actors have fallen into homelessness when they fall to addiction. No one is immune to harmful substances, no matter how much money or fame they have.