Nearly one in four Minnesotans went without health insurance for some period during 2007-2008, a national advocacy group said Tuesday, a sign that rising costs are putting medical coverage beyond the reach of more consumers and employers, especially in a weak economy.

Minnesota, however, had the lowest rate of uninsured people among the 49 states studied, continuing its long tradition of extensive private and public coverage.

Nationally, one in three non-elderly Americans had no health coverage at some point in the two-year span, the study found.

"We have reached a point where almost everyone in this country has had a family member, a neighbor or a friend who is uninsured,'' said Ron Pollack, executive director of Families USA, the Washington, D.C., advocacy group that commissioned the study.

"Premiums have been rising more than four times faster than peoples' earnings,'' Pollack added. "As premiums absorb a larger share of family budgets, people who used to take health insurance for granted are joining the ranks of the uninsured.''

Pollack said he expects the number of uninsured to rise, nationally and in Minnesota, as more people lose their jobs in the recession.

(Massachusetts, which adopted a universal-coverage system part way through the study period, was excluded.)

Pollack's group advocates federal action to expand access to health insurance.

The numbers released Tuesday are higher than those reported by the federal government because Families USA counts everyone who went uninsured for at least one month during the two-year span. The U.S. Census Bureau counts only those who lack insurance for an entire year. By that measure the share without insurance was 15.3 percent nationally and 9.9 percent in Minnesota in 2007, the latest year available.

Pollack's group uses the broader measure to show that a wide spectrum of Americans are at risk of some disruption in their medical coverage. In Minnesota, for example, more than 80 percent of the uninsured were members of working families and many were far above the poverty line.

The number of people with a spell of not being insured has risen by nearly 9 percent since 2004, the study estimated.

The most recent study by the Minnesota Department of Health, for 2007, showed no increase in the share of Minnesotans who were uninsured, but officials said that number might rise because of the recession.

Staff writer Warren Wolfe contributed to this report.