The second report released Thursday comes from the Commonwealth Fund, with the title, "Who Are the Remaining Uninsured and Why Haven't They Signed Up for Coverage."
The group notes that about 20 million Americans have gained health coverage since 2010, when the ACA first began taking effect, with a provision that allowed people under the age of 26 to stay on their parents' health plans.
"Yet an estimated 24 million people still lack health insurance," the report said.
Of that 24 million, about 21 million of them — 88 percent — have incomes below about $16,243, were young adults, worked at small firms, and/or are Latino, according to the Commonwealth Fund.
In 2013, Latinos, who have the highest rates of uninsurance of any ethnic group, comprised 29 percent of the uninsured population.
Latinos now make up 40 percent of the uninsured, according to the report, which notes that is "more than twice their representation in the overall population."
At the same time, whites, who previously made up half of the uninsured, now comprise 41 percent of the uninsured.
The report noted that 34 percent of the remaining uninsured have incomes low enough to qualify them for Medicaid, but live in one of the 20 states that have not adopted Obamacare's provision that allows nearly all poor adults to be covered by that program, with significant federal financial assistance.
In states that did not expand Medicaid under Obamacare, 41 percent of adults with incomes below $16,243 were uninsured as of the summer of 2013. By 2016, the uninsured rate among that population had fallen just to 35 percent this year — which is actually 1 percent more than in the past two years.
However, in the states that did expand Medicaid, the uninsured rate among poor adults fell from 30 percent in 2013, to only 17 percent this year.
The report found that almost two-thirds of uninsured adults who knew about Obamacare insurance marketplaces, which offer subsidized coverage to low- and middle-income people, had not visited those exchanges "because they did not think they would be able to afford coverage."
At the same time, the report said, more than half of the uninsured adults actually had incomes in a range that made them eligible for federal subsidies that could reduce the cost of their Obamacare exchange plan coverage.