While all States have seen increases in insurance coverage since the ACA’s major coverage provisions took effect in the beginning of 2014, the extent of those gains have varied widely by State. Notably, States that have expanded Medicaid under the ACA have seen larger coverage gains on average, particularly if they started with a larger uninsured population. If Medicaid non-expansion States had seen coverage gains comparable to those seen by Medicaid expansion states with similar uninsured rates, the uninsured rate in these states would have been nearly 3 percentage points lower in 2015, increasing the magnitude of these states’ coverage gains since 2013 by almost two-thirds.

https://www.whitehouse.gov/blog/2016/09/13/income-poverty-and-health-insurance-united-states-2015?utm_campaign=digest&utm_medium=email&utm_source=app