The quality of healthcare Americans receive depends largely on where they live, with insurance coverage, access to preventive medicine and disease treatment varying widely from state to state, according to a study released on Thursday by the Commonwealth Foundation.

Where you live matters, said the foundation's Vice President Cathy Schoen, who co-authored the study for the private research group, in a conference call with reporters. And it shouldn't.

The report found that all of the states that have made healthcare reforms provide better access to medical treatment and prevention and mostly avoid costly hospital procedures.

Residents of Vermont have the best healthcare in the country, the foundation said. The small northern state, which embarked on a radical plan to provide all citizens with healthcare less than a decade ago, also leads the nation in equity, or making sure that people of lower income groups have healthcare.

The report comes as the U.S. Congress inches closer to finalizing a plan to reshape healthcare. So far, drafts of the plan have emphasized relying on the states to operate insurance exchanges and possibly to extend more health insurance to families with lower incomes.

The patterns indicate that public policies, plus state and local health care systems, can make a difference, according to the report, which was also conducted by Joel Cantor, director of the Center for State Health Policy at Rutgers University.

Hawaii followed Vermont, and Iowa was ranked third on the scorecard. Neither state has a plan to reform healthcare, but Minnesota, which has created public-private collaborations on healthcare, ranks fourth, followed by Maine, which has also implemented sweeping reforms. Massachusetts -- the Vermont neighbor that recently began a universal health insurance program -- was seventh.

At the other end of the spectrum, Mississippi has the worst healthcare, according to the scorecard. Oklahoma fares mildly better, followed by Louisiana and Arkansas.

Generally, the report found, states in the South, Southwest and lower Midwest have worse insurance rates and less access to good medical treatment.

In an example of the disparate coverage, the report found that more than 25 percent of children in the bottom five states did not receive recommended vaccinations, while in the top five states, only 10 percent went without vaccinations.

MOST ADULTS DON'T HAVE HEALTH INSURANCE

At the national level, the dearth of health insurance for adults resembles an epidemic, Schoen said.

Since the start of the decade, the number of states with high uninsured rates for adults -- which the report measured as 23 percent or higher -- rose to nine from two. While the number with rates of 14 percent or less dropped to 11 from 22.

From 2007 to 2009, health insurance coverage of adults aged 18 to 64 declined in 31 states.

The number of states with high rates of uninsured children, on the other hand, dropped, as the federal government expanded its support of the Childrens Health Insurance Program, which targets children of low-income families.

Many states have expressed reservations about a national healthcare plan during the longest and deepest recession in 70 years. With their revenues plummeting, they say they cannot take on additional costs that may come with a federal plan.

But the Commonwealth Foundation said a national plan would give states crucial support.

The erosion of insurance coverage...and the high uninsured rates in many states underscores the need for national reform and federal action to extend affordable insurance and ensure access for everyone, it said.