Abortion opponents, who believe that the procedure destroys human life, argue that Roe is simply bad law. The Supreme Court stepped over the line in the ruling, they say, finding a constitutional right where there wasn’t one and sweeping away established laws in dozens of states.

Abortion should be decided in state legislatures, said Steven Aden, general counsel of Americans United for Life. It would probably remain mostly legal in a third of the states, mostly illegal in another third, and be the subject of a furious fight in the rest, he said.

“That’s the fight we think America should have,” Mr. Aden said.

At least six states are down to one clinic — North Dakota, South Dakota, Wyoming, Kentucky, Mississippi and West Virginia. At times, Arkansas and Missouri had been a seventh and eighth.

The fight in Arkansas centers on medication abortions, which currently account for nearly a third of all abortions, according to the Guttmacher Institute. Medication abortions enable women up to 10 weeks pregnant to take two pills, the first supervised by a doctor and the second at home, to terminate a pregnancy without surgery. It was approved for use in 2000.

When the medication abortion law went into effect in Arkansas, it left only one clinic for a state of three million. That meant women from northwest Arkansas, where Dr. Ho practices, had to either go out of state or make a 380-mile round trip to Little Rock for a surgical abortion.

Now the number of clinics is back up to three. But many other barriers remain: a ban on abortions after 20 weeks; a 48-hour waiting period, which requires women to make two or three trips to the clinic; parental consent for minors; doctors unable to dispense medication abortion pills remotely by video.

“If you’re a woman in Arkansas, and you’re almost 200 miles away from a clinic, have a 48-hour waiting period, and a job that doesn’t give you sick leave or flexible hours, then your access to abortion has already been banned,” said Helene Krasnoff, head of litigation at Planned Parenthood Federation of America. A regional branch of the organization, Planned Parenthood Great Plains, runs the clinic in Fayetteville, which provides medication abortion only.