The uninsured rate in Minnesota has fallen by more than 40 percent since the Affordable Care Act's coverage expansion started, a new report from the State Health Access Data Assistance Center shows.

The analysis appears to be the first assessment of how a state's uninsured rate has changed since the insurance expansion began in October. It shows that, between September 2013 and May 2014, the number of uninsured Minnesotans fell from 445,000 to about 264,500.

Most of the increase in coverage was through public programs, rather than people gaining private insurance through the exchange. Enrollment in two of Minnesota's largest public coverage programs, Medical Assistance (the state Medicaid program) and MinnesotaCare (a subsidy program for low-income residents), grew by 155,000 during the open enrollment period.

Coverage in the private individual market, meanwhile, only grew slower, with 36,000 gaining coverage both through the state exchange, MNSure, and outside of it.

Not all states are likely to see such steep declines in the uninsured rate, largely due to the fact that 24 states did not participate in the Medicaid expansion this year. That's the program that really drove the uninsured rate down in Minnesota.

Gallup data suggests that, nationally, the uninsured rate has fallen by just about 22 percent since the insurance expansion began, from 17.1 percent during the last quarter of 2013 to 13.4 percent in the second quarter of 2014.

The Medicaid expansion seems to be playing a big role, then, in Minnesota's steeper decline in uninsured rates. Either that, or the state's relatively unique ads featuring a giant Paul Bunyon who really needs health insurance coverage.