Ever since Texas laws closed about half of the state's abortion clinics in 2013, researchers have been trying to understand just how much burden those laws place on women who are trying to access abortion. That's important because the Supreme Court is now considering those laws as part of Whole Woman's Health v. Hellerstedt, the court's most consequential abortion case in decades. If it finds that the laws place an "undue burden" on women, they'll likely be struck down.

Researchers with the Texas Policy Evaluation Project (TxPEP), looking into exactly that, have already found that some women had to wait as much as three weeks longer for an appointment. Some women they've interviewed weren't able to secure an abortion at all, due to the logistical and financial barriers.

Now, TxPEP has published a significant study, in the American Journal of Public Health, on the effects of HB2, the omnibus anti-abortion bill that the Court could end up partially striking down. The study shows just how many burdens were placed on women as a result of the clinics closed by the law.

Women had to travel an average of four times as far to get to a clinic

Researchers surveyed 398 Texas women, comparing women whose nearest abortion clinic was closed in mid-2014 with those whose nearest clinic was still open in April 2013, shortly before the Texas legislature debated HB2.

The results were striking. Of the women surveyed, 38 percent lived in a zip code where the closest clinic was open in 2013 but closed in 2014.

One key finding: Women whose nearest clinic hadn't closed had to travel an average of 22 miles, while women whose nearest clinic had closed traveled an average of 85 miles — almost four times as far. And a quarter of women in the latter group had to travel more than 139 miles to get an abortion.

This was the case even six months after HB2 went into effect, when abortion providers would have had at least some time to adjust to the initial chaos of closures.

Women faced higher costs and other difficulties

Women whose nearest clinics closed had a tougher time by just about every measure: They had to travel farther and pay more out of pocket for things like gas, hotels, and child care.

They were less likely to be able to access medication abortion instead of surgical abortion if they wanted it — probably because Texas law requires four different doctors' visits for medication abortion, which is a lot tougher to manage when you live far away.

Unsurprisingly, they were also more likely to report that it was "somewhat hard" or "very hard" to get care.

Women whose nearest clinics closed also faced more burdens — for instance, they were more likely to both travel more than 50 miles and spend more than $100 on the trip. Twenty-four percent of women in the closure group reported facing three or more different kinds of burdens, compared to just 4 percent of women whose clinics remained open.

And the study only looked at women who eventually got their desired abortion — so it couldn't account for the women who weren't able to get one at all because the burdens were too high.

"This study is unusual in its ability to assess multiple burdens imposed on women as a result of clinic closures, but it is important to note that the burdens documented here are not the only hardships that women experienced as a result of HB2," said study author Liza Fuentes in a statement.

Strangely, there was no significant difference between the two groups of women in how far along they were in their pregnancy when they had an abortion. That's inconsistent with other TxPEP research that found, after HB2 passed, a small but significant increase in second-trimester abortion procedures, which are not quite as safe and a lot more expensive compared to the first trimester procedures.

But that could be explained by a couple of things, the researchers wrote. Either the long wait times forced by HB2 are affecting everyone equally, or the differences were too small to show up in this study.

It's still clear, the researchers said, that the clinic closures after HB2 passed "resulted in significant burdens for women able to obtain care."