Vice President Joe Biden visits a sign up site for the Affordable Care Act at the Carlos Rosario International Public Charter School, March 31, 2014 in Washington, DC. Open enrollment for the first yearly sign-up period closes at the end of Monday. (Photo by Drew Angerer/Getty Images)

The non-partisan Urban Institute estimates that about 5 million Americans have become newly insured over the last year, an early indication that the Affordable Care Act has achieved one of its chief aims, reducing the number of Americans without health care coverage.

The Obama administration announced this week that about 7 million Americans enrolled in health care plans through the exchanges set up under the law, but that number includes some number of people who previously had insurance, so it’s not clear if those people actually got insurance because of “Obamacare.”

The Urban Institute study looks more carefully at the question of who had been previously insured. They estimate that about 17.6 percent of Americans between ages 18 and 64 were uninsured in the early parts of 2013, compared to about 15.2 percent now. That would constitute about 5.4 million adults who have gained insurance.


Unsurprisingly, states that have chosen to expand their Medicaid programs under the law have seen much larger increases than those who have not.

To be sure, this report is preliminary. The authors note it does not include data from the last week in March, when more than 1 million Americans enrolled. And it does not tell us if people are satisfied with their insurance and its costs or simply enrolled because the law requires them to do so.