Nearly 82 million people - one third of the U.S. population younger than 65 - lacked health insurance at some point over the past two years and most of those were uninsured for more than nine months, says a study by the private group Families USA.

The problem reaches deep into the middle-class, affects African-Americans and Hispanics disproportionately and is most pronounced among people younger than 25, according to the group's analysis of census data.

Numerous studies have associated a lack of health insurance with poorer health and earlier death, as well as delayed and inadequate medical care. Read more.