Iowa was one of 26 states in which the Economic Security Index improved by a statistically significant amount.
Twenty five other states had larger levels of decline in economic insecurity, with the largest declines in Arizona, Utah, Alaska and Mississippi.
Four states had statistically significant increases. They were Texas, Kansas, South Dakota and Montana.
The index was developed by Yale political scientist Jacob Hacker and a team of researchers, with the support of the Rockefeller Foundation.
The index decline by an average of of 1.3 percentage points in all of the states. It was the largest nationwide decline in the last quarter century.
The index tracks the proportion of Americans who see their household income after paying for medical care and servicing their debts decline by 25 percent or more from one year to the next, and who lack sufficient financial wealth to make up the lost income.
In 2011, 17.9 percent of people in Iowa experienced the major economic losses measured by the ESI, compared with 18.3 percent in 2010.