Amid an escalating Republican assault on reproductive rights and a looming U.S. Supreme Court reckoning, women and allies across the United States and around the world took to the streets Saturday to #RallyForAbortionJustice and defend Roe v. Wade.

Tens of thousands of demonstrators marched in Washington, D.C, New York City, Los Angeles, and more than 600 other cities and towns, according to Women’s March, the event organizer.

“No matter where you live, no matter where you are, this moment is dark—it is dark—but that’s why we’re here,” Alexis McGill Johnson, president of Planned Parenthood, told participants at the Washington, D.C. protest. “It is our job to imagine the light, even when we can’t see it. It is our job to turn pain into purpose. It is our job to turn pain into power.”

At the Houston rally—where signs read “Abort Abbott” in protest of S.B. 8, Texas’ draconian abortion law signed earlier this year by Republican Gov. Greg Abbott—more than 10,000 people turned out, with many chanting, “Our bodies, our choice.”

In Washington, D.C., Women’s March executive director Rachel O’Leary Carmona described the wave of GOP anti-choice laws in at least 16 states as an “unprecedented attack” on reproductive rights.

“For a long time, groups of us were ringing the alarm bell around abortion access and many of us were told we were hysterical and Roe v. Wade will never be overturned,” Carmona told USA Today. “But now it’s clear that our fears were both rational and proportional.”

Women’s March says that by refusing to block the Texas law—which bans abortions after six weeks without exceptions for rape or incest, and offers $10,000 bounties for vigilantes who successfully sue anyone who “aids or abets” the medical procedure—the Supreme Court “effectively took the next step towards overturning Roe v. Wade.”

In May, the Supreme Court announced it will hear a challenge to Mississippi’s near-total abortion ban, a case that author Lauren Rankin warned “may very well be the death knell for Roe v. Wade” given the high court’s conservative supermajority.

Nearly all House Democrats came together last week to pass the Women’s Health Protection Act (WHPA) in response to the Texas law and amid mounting fears that the Supreme Court will overturn Roe. According to the advocacy group Equal Access to Abortion, Everywhere, the WHPA would establish “a statutory right for health care providers to provide, and their patients to receive, abortion care free from medically unnecessary restrictions, limitations, and bans that delay, and at times, completely obstruct, access to abortion.”

However, the bill faces an uphill battle in an evenly split Senate in which anti-choice Democrat Joe Manchin of West Virginia and Sen. Bob Casey (D-Pa.) oppose the measure.

Sen. Elizabeth Warren tweeted Saturday that Americans “support the right to a safe, legal abortion.”

Speakers at Saturday’s rallies emphasized the harm caused by anti-choice laws. Planned Parenthood of Illinois senior director of public policy Brigid Leahy told the Associated Press at the Springfield march that women started traveling to Illinois two days after the Texas law took effect.

“They are trying to figure out paying for airfare or gas or a train ticket, they may need hotel and meals,” she said. “They have to figure out time off of work, and they have to figure out childcare. This can be a real struggle.”