WASHINGTON – 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 were uninsured for more than nine months, an advocacy group said.

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 Families USA’s analysis of Census data.

The study, expected to be released today, found that 8.5 million Texas residents, or 43.4 percent of the nonelderly population there, did not have health insurance – the highest rate in the country.

Other states where more than 35 percent of people younger than 65 were uninsured were: New Mexico, 42.4 percent; California, 37.1 percent; Nevada, 36.8 percent; Louisiana, 36.2 percent; Arizona, 35.7 percent; Mississippi, 35.1 percent, and Oklahoma, 35 percent.

Numerous studies have associated a lack of health insurance with poor health and early death, as well as delayed and inadequate medical care.

In Maine, where 26.9 percent of the nonelderly population was uninsured, Gov. John Baldacci said the new report understates the magnitude of the problem.

“When you pierce beneath the surface, a lot of people may have insurance, but it’s really like catastrophic coverage,” not a comprehensive insurance policy, Baldacci said.

The state’s new Dirigo Health Plan is intended to offer Maine residents health insurance that is subsidized by the state and participating employers. Coverage is expected to begin in January, Baldacci said.

Ron Pollack, Families USA’s executive director, said fast-rising health care costs, a soft labor market in which employers are passing more health costs to workers, and reductions in state safety net programs are resulting in substantial increases in the number of uninsured.

The study focused on Americans younger than 65 because older Americans are covered by the federal government’s Medicare program.

Typically, the Census Bureau reports the number of uninsured Americans as those without health insurance for the entire year. The bureau reported last September that 43.6 million were uninsured for all of 2002, and updated figures will be released this summer.

But the ranks of the uninsured grow when a longer time span is examined and when also including those who are uninsured for less than a year.

Even among families with incomes of $75,000 a year and up, 13.5 million people were without insurance for part of 2002-2003, the study said.

The numbers were especially high for minorities, “disproportionately represented in low-wage jobs and jobs in sectors that are less likely to have health insurance benefits,” the report said.

Nearly 60 percent of Hispanics and 43 percent of blacks were uninsured. Among whites, the rate of uninsurance was 23.5 percent.

The numbers are projections developed by the Lewin Group consulting firm based on Census data.

Families USA issued a similar report last year showing that 75 million people were without insurance for part of 2001-2002. But the two reports are not directly comparable because the earlier study relied on some Census information dating back to 1998, executives at the Lewin Group said.