The implementation of the Affordable Care Act (aka “Obamacare”), for all its controversies and complexities, has dramatically reduced the percentage of Americans who lack basic health insurance. But the United States continues to rank at the top of the wealthy industrialized nations of the world in the portion of its residents who lack health insurance.

One reason is the refusal of 20 red states to accept the optional expansion of Medicaid — even though in its first years the expansion would be paid for entirely with federal dollars. This strikes liberals as somewhere between crazy, stupid and cruel, and it does account for a significant portion of the remaining uninsured in America.

In states that accepted the expansion, families with near-poor income levels that are just above the old level are now eligible for Medicaid. But they still have to enroll to get the benefits and not all have done so.

Drew Altman of the Kaiser Family Foundation and who writes for the Wall Street Journal on health insurance issues has a column today that elevated my understanding of how the Medicaid expansion issue fits into the overall picture of Obamacare’s implementation and impact.

The column compared the two largest population states, California and Texas, which are also the two states with the largest number of uninsured. California, a solid blue state, accepted the Medicaid expansion, which significantly reduced the number of uninsured Californians, a fact that undoubtedly contributes to it ranking second, behind Texas, in the number of uninsured.

Texas, a bright red state, rejected the Medicaid expansion, which leaves 766,000 Texans — who would qualify for Medicaid if Texas would accept the expansion — uninsured.

And yet California nonetheless ranks second in the number of its residents uninsured with 3.8 million Californians uninsured.

Of that 3.8 million, 1.4 million are eligible for Medicaid but haven’t enrolled. A much smaller portion, 623,000, would be eligible for the tax credit/subsidy to help them pay for health care under the Obamacare-created marketplace, but they have not availed themselves of that opportunity. And another 1.8 million residents of California are uninsured either because their incomes are too high or they are not legal residents. (I presume most of those with incomes too high could afford some kind of insurance but choose not to.)

Texas also has uninsured residents for all of those reasons who make up the majority of the 4.4 million uninsured Texas residents.

I’m in the category of those who think the rejection of the Medicaid expansion by those 20 states is somewhere between crazy, stupid and cruel. But even if they reversed that decision, the United States would still rank at the top of the wealthy industrialized nations of the world in the portion of its residents that lack health insurance.