The abortion rate dropped to a nearly 50-year low in 2017, the lowest level recorded since Roe v. Wade, the landmark Supreme Court decision that legalized the procedure.

In 2017, the most recent year available, the abortion rate was 13.5 abortions per 1,000 women aged 15 to 44, according to a study published Wednesday morning by the Guttmacher Institute, a pro-abortion access research organization. That's an 8% decline from 2014, the last time Guttmacher calculated the United States' abortion rate, and 54% lower than when the group recorded the peak rate in 1980.

Guttmacher attributed the decline to two factors: a declining pregnancy rate and a growing disparity between abortion access in liberal and conservative states. That divide stems largely from laws targeting the operations of clinics that provide abortions, a style of regulation known as a Targeted Regulation of Abortion Provider – or TRAP – law.

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While all regions — Northeast, South, Midwest and West — recorded declines, rates dropped much more dramatically in states where the number of clinics had also fallen.

Texas recorded the largest drop in the number of abortion-providing facilities between 2014 and 2017, falling to 35 from 44, according to Guttmacher. During that same time period, the abortion rate fell 3% and the state's legislature passed 10 additional laws restricting and regulating the procedure, the most significant being a requirement that abortion doctors have admitting privileges at a nearby hospital.

When that regulation was passed, it forced the closure of a handful of clinics in Texas that didn't reopen even when the law was struck down by the Supreme Court, according to Guttmacher.

"Your zip code or your income should never determine whether you can have an abortion," said Guttmacher president Dr. Herminia Palacio on a call with reporters Tuesday ahead of the study's release.

In Ohio, lawmakers in 2015 updated an existing law to require abortion providers to be within 30 miles of a public hospital with which they had a public transfer agreement. That change, among other restrictions, contributed to a decline in abortion-providing clinics from 12 in 2014 to 9 in 2017. During the same time frame, the abortion rate dropped 9%, according to Guttmacher.

"Pregnant people who want to obtain an abortion are made to jump through hoops and those who can't are forced to remain pregnant," said Elizabeth Nash, a senior states issues manager at Guttmacher, on a call with reporters.

According to Guttmacher, the 10 states with the largest increase in the number of clinics saw declines in their abortion rates, indicating that "the concurrent expansion of abortion care and decrease in abortion rates was taking place in the context of an increase in comprehensive health care."