Maine’s Washington County has the dubious distinction of being the northernmost outpost of the Confederacy.

At least it looks that way on a map created by The New York Times that shows the percentage of residents without health insurance in all of the 50 states.

Washington County has the highest rate of uninsured residents in Maine — 14 percent — as opposed to 9 percent in Cumberland County and 8 percent in York. In fact, no other county in New England has such a high rate of people without health insurance. Neither does any county in New York state or Pennsylvania. In fact, you would have to go all the way to the southern tip of West Virginia before you can find such a high rate.

The map changes dramatically, however, when you get into the states of the old Confederacy. North Carolina, South Carolina, Georgia, Alabama, Mississippi, Tennessee, Florida and Texas all average rates of uninsurance at or above Washington County’s levels. This is not just a quirk of history or geography. This is the result of policy choices made in Republican-controlled states of the Old South that rejected Medicaid expansion under the Affordable Care Act, and as a result have chosen to put their residents’ lives at risk.

Since Maine is the only state in the Northeast to have made that choice, its poor are suffering along with the people who live in the southern part of the country.

The Affordable Care Act has succeeded in reducing the number of people without health insurance, but the data show the improvement hasn’t been distributed equally. The optional Medicaid expansion helps people with incomes below 138 percent of the federal poverty line (or about $16,000 a year for an individual), who work in jobs that rarely provide health benefits.

In Maine, an estimated 70,000 people would have been able to obtain affordable health care if the state had accepted the federal funds.

It’s important to remember that this is not just about insurance, it’s also about health.

People without insurance are less healthy than people with coverage. Thousands of avoidable deaths every year result from undetected cancers, mismanaged chronic conditions and lack of access to life-saving medical procedures. Millions of dollars are wasted in lost productivity, charity care and bad debt.

The rejection of the almost entirely federally funded Medicaid expansion results from a hatred of federal authority that has festered in the South since it was invaded and occupied by a victorious federal army a century and a half ago.

Given Maine’s history as a part of that force, its ideological alliance with the Southern states makes as little sense from a historical perspective as it does from an economic and humanitarian one.

Maine should not fight this common-sense medical reform any longer. It’s time to rejoin the Union, and expand Medicaid.