But whatever you make of those topline numbers, one thing seems certain: an abortion ban would disproportionately affect women from non-white and low-income backgrounds.

To understand how that works, we need to look at the way distance acts as a deterrent against abortion access. Among women overall in the 1970s after New York legalized abortion but before Roe v. Wade was decided, every 100-mile increase in distance between a patient and a New York clinic corresponded to a 12 percent decrease in abortion rates, the researchers wrote.

The challenges posed by distance are still valid today -- and they affect non-whites at far greater rates than whites. In the scenario involving a 31-state ban, minorities would see their abortion rates drop 1.8 percentage points more than whites. In the extreme example of a 46-state ban, the difference would be 12.3 points.

"If race serves as a crude proxy for socio-economic status," the authors conclude, "and if distance proxies the cost of an abortion, then the racial differences are consistent with less well-off women being more sensitive to the availability of abortion services than more advantaged women."

But we don't need to take the researchers' word for it. Dr. Patrick Whelan, a Harvard rheumatologist who's studied abortion rates in Massachusetts, argues that financial incentives don't work with abortion they way they might in other industries. In a phone interview last week, Whelan cited data on women who choose to pay out-of-pocket for their abortions even when they could get the procedure done for free or at a discount thanks to insurance.

"Whether that's a modesty issue, or they don't think it might be covered, or they don't want a public record of it someplace," Whelan said, "cost is not a deterrent for a lot of people." Whatever the reasons behind women's choices, Whelan's larger point is this: financial barriers aren't enough to dissuade women from getting an abortion if they want one.

At first blush, Whelan and the NBER study appear to be saying different things. The former suggests that abortions will continue irrespective of the price tag, while the latter suggests cost really is a limiting factor for women in that living farther away from a legal abortion clinic tends to depress abortion rates.

These statements aren't really mutually exclusive, though; they're just different ways of explaining how women of different backgrounds respond to the problem of cost. Where they agree is that the wealthy, who are generally white, are better able to eat the cost of extra travel compared to low-income non-whites. In other words, white women are able to go to longer lengths (literally) to get a legal abortion.

Non-white and low-income women aren't so lucky. For them, an abortion ban would mean either carrying their unplanned pregnancies to term -- something the NBER paper predicts could happen to some degree, and which would likely be exacerbated by conservative attempts to limit contraception access at the same time that they crack down on abortion -- or resorting to unsafe, illegal abortions. These procedures, by their very nature, would be ignored by official abortion figures so that to speak of the "gains" of a ban would be to turn a blind eye to a very nasty black-market business. It'd also create new headaches for states: between the threat to public health posed by underground abortions, and the rise of teen birth rates; the added economic burden on state social and health-care services; the mockery it'd make of public statistics; and their inherent racial and socio-economic unfairness, it's hard to see how abortion bans would advance anything except ideology.

Average Distance to the Nearest Abortion Provider With

Hypothetical Abortion Bans in 31 States

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