Not all this growth is due to Obamacare; it can't account for the slight growth in Medicaid enrollment in that didn't participate in the health law's expansion. But it is possible the law had an indirect effect in those places. People who were already eligible for Medicaid, but not enrolled, for example, may have heard about the coverage expansion and explored their options. These signups by people who were already eligible for coverage are known in health policy circles as the woodwork effect. And it seems to be especially strong in some non-expansion states. For example, South Carolina, which has not expanded its Medicaid program, has seen enrollment rise by 14.4 percent anyway. Montana, another state opting out of Obamacare, has had 10.4 percent growth. - www.vox.com