The law’s passage, without a single Republican vote, capped decades of efforts to enact a broader health insurance system. Medicaid and Medicare passed in the 1960s, but did little to help workers who did not receive insurance through their jobs. Presidents Nixon, Carter and Clinton all tried and failed to win approval for expanded coverage, and the number of uninsured Americans grew to nearly a fifth of adults under the age of 65 by 2010, the year the Affordable Care Act passed.

The findings from the census data could inform the national dialogue, especially in this election year. Hispanics are a powerful voting force and the law is viewed favorably in Hispanic neighborhoods. But whether the sharp increase in coverage rates for Hispanics will translate into votes for Democrats who supported the law, or whether some Republicans might temper their vows to repeal it, is not clear. And the fact that so many who benefited under the law were not citizens (or voters) — 1.2 million out of the total 8.7 million who got health insurance in 2014 — could set off a new round of debate in a year when immigration has become a deeply polarizing issue.

About 60 percent of those noncitizens were Hispanic, mostly natives of Mexico and Central America who had been living in the United States for decades. Another third were Asian, mostly newer arrivals living in states like California, New York and Texas. Illegal immigrants are not eligible for insurance under the law, but legal immigrants can qualify for subsidies in the insurance exchanges and those who have been in the country for more than five years can qualify for Medicaid.