A new U.S. Census report shows that while the number of people without medical insurance rose only slightly from 2007 to 2008, more people were covered by government programs as employer-sponsored coverage continued to decline.

The total number of uninsured remained at just over 15 percent in 2008, increasing from 45.7 million to 46.3 million, the Census found. However, the percentage of people covered by private and employer plans fell (67.5 percent to 66.7 percent and 59.3 percent to 58.5 percent, respectively) while the ranks of those insured by government plans rose to 29 percent from 27.8 percent, driven by increases in both Medicaid and Medicare enrollment.

The 2008 survey was the first to include questions on health coverage, which the Census Bureau said it added to assist in fairly distributing resources to states. Though the increase in the uninsured is not dramatic, some experts noted that the numbers mask the true extent of the problem.

"These modest increases in the uninsured are only the tip of the iceberg," said Elise Gould, director of health policy research at the nonprofit Economic Policy Institute, in a Sept. 10 analysis. "Given that the economy has deteriorated significantly since 2008, the current state of health insurance is worse than [the Census] report shows."

Insurance status also varied by income and place of residence, according to the data. The percentage of uninsured increased as income decreased, with the highest percentage of uninsured (24.5 percent) occurring among those in households making less than $25,000. In households making $25,000 to $49,000 a year, 21.4 percent were uninsured.

Geographically, the Northeast and Midwest had the lowest percentage of uninsured (11.6 percent), and the West and South recorded the highest percentages (17.4 and 18.2 percent, respectively). Massachusetts, which adopted almost universal coverage in 2006, had the lowest rate of uninsured among states, at 5.5 percent. Texas ranked highest with 25.1 percent of its residents uninsured.

Geographic disparities are driven by differences in income levels, but other factors are also in play, said Peter Cunningham, a senior fellow at the Center for Studying Health System Change. "Areas of the country dominated by large employers and union jobs (such as the Northeast and Upper Midwest) have greater availability of employer-sponsored coverage, while areas dominated by small employers, service sector and non-union jobs (such as the Southeast) have less," he said.

Other factors behind the statistics include state eligibility levels for public programs, such as Medicaid, and demographics, Cunningham added. For example, he said, areas of the country with a high proportion of Hispanic immigrants, such as Texas, tend to have higher uninsured rates.

The most alarming news in the report, according to Karen Davis, president of the Commonwealth Fund, was the percentage of people younger than 65 who do not have insurance. Just over 20 percent of adults 18 to 64 years old were uninsured in 2008, up from 19.6 percent in 2007, according to the report, and these numbers may understate the problem, she said. The Census report counts people insured early in 2008 as insured for the year, but many people lost coverage later in the year because of the recession and rising unemployment, Davis noted.

Dr. Risa Lavizzo-Mourey, president and chief executive of the Robert Wood Johnson Foundation, said that the Census numbers reinforce the importance of achieving meaningful health-care reform.

"We are at a unique moment when lawmakers have the chance to help millions of Americans better access stable, affordable health insurance," she said in a prepared statement. "Now is the time for advocates, policymakers and the public to focus on where they agree, and be willing to compromise where they don't, in order to finally take action to fix what's broken."

However, Cunningham said he doubted that the Census report would influence the current debate about reform.

"By now, it's pretty well understood by policymakers in both parties that the number of uninsured is high and continues to grow," he said. "The debate is no longer about whether there's a problem, but rather what to do about it."

The full Census report -- "Income, Poverty and Health Insurance Coverage in the United States -- 2008," released in September -- is available online at http://www.census.gov/prod/2009pubs/p60-236.pdf.