An estimated 15.5 million fewer U.S. adults were uninsured in March 2016 than September 2013, shortly before the Health Insurance Marketplaces opened for enrollment, according to the Urban Institute's latest Health Reform Monitoring Survey. The proportion of uninsured non-elderly adults declined 7.7 percentage points over the period, to 9.9%, the survey estimates. States that had implemented the Affordable Care Act’s Medicaid expansion by January 2016 saw a decline of 8.5 percentage points, compared with a drop of 6.5 percentage points in non-expansion states. They also saw greater gains in adults with continuous coverage. The survey is funded in part by the Robert Wood Johnson Foundation.