The Affordable Care Act (ACA) halved the rate of those Californians who are uninsured from 6.5 million in 2013 to 3.3 million in 2015, according to Census Bureau figures in this new data brief. Two factors drove the decline: Medi-Cal expansion and subsidies for those purchasing insurance through the state health marketplace, Covered California.

The brief, along with breakouts for select counties, reports the primary beneficiaries of those two programs -- low-income earners, young adults, part-time workers, and Latinos -- have the most to lose from repeal of the ACA. Every county in California saw dramatic declines in uninsurance between 2013 and 2015, and authors of the brief suggest a repeal of the law may result in a future uninsurance rate that is higher than it was before implementation of the ACA.