The clinic, in the works for more than two years and part of Planned Parenthood of the St. Louis Region and Southwest Missouri , was built in secret. Dr. Colleen McNicholas, chief medical officer for the affiliate, said it was done that way because there had been difficulties with contractors in the past. At one clinic in Springfield, Mo., a company that was supposed to install fiber-optic lines dragged its feet for more than a year, she said. At another, cabinetmakers walked off the job, leaving the clinic without any cabinets.

“There have been many examples where the politics of providing reproductive health care has really delayed the project,” Dr. McNicholas said.

Missouri women have been traveling out of state to get abortions for years. In 2009, nearly half of abortion patients in Kansas came from Missouri, roughly the same as in 2017. Illinois is another destination. Out-of-state residents accounted for about 14 percent of abortions in Illinois in 2017, double the percentage in 2012, according to data from Illinois and the federal government.

Many of those patients are from Missouri. At the Hope Clinic for Women, a private clinic in Granite City, Ill., not far from downtown St. Louis, about half of all abortion patients are from Missouri.

Planned Parenthood itself drove some of the movement into Illinois. In the spring of 2018, it began sending women seeking abortion through medication rather than through a surgical procedure across the Mississippi River to a small storefront clinic it operated in Illinois. Doctors had balked at a Missouri rule to conduct pelvic exams for medication abortion patients, saying it was medically unnecessary.

Medication abortion happens early in pregnancy — up to 11 weeks gestation — and involves two sets of pills, one taken at the clinic and one at home. It was approved by the federal government in 2000, and by 2017, accounted for more than a third of abortions in the country, according to the Guttmacher Institute, which tracks abortion statistics.

Samuel Lee, an abortion opponent in St. Louis, who helped push Missouri lawmakers to pass a sweeping abortion restriction bill this spring, said he thought the anti-abortion movement was too focused on physical clinics at a time when a rising share of abortions are done through medication, with some women ordering pills online.