Thousands are protesting abortion at the March for Life in Washington

It's the largest anti-abortion demonstration in the world.

Thousands of Americans are in Washington D.C. on Friday for the largest anti-abortion demonstration in the world.

It's the 44th annual March for Life – an event that's held every year on or around the anniversary of Roe vs. Wade. Marchers gather at the nation's capitol to protest the Supreme Court decision that ruled abortion legal across the U.S. in 1973.

Minnesota's March for Life already happened last weekend, drawing an estimated 4,500-5,000 anti-abortion protesters. But the march in Washington is the main event.

A rally takes place at noon on the grounds of the Washington Monument, followed by a march toward the Capitol. Priorities identified by the marchers include bringing an end to federal funding of women’s health organization Planned Parenthood, and the closure of more abortion clinics.

What began as a small demonstration in 1974 "rapidly grew to be the largest pro-life event in the world," the website says. The march’s biggest year was on the 40th anniversary of Roe vs. Wade in 2013, the NY Daily News says, with an estimated 600,000 people showing up.

And this year, many news organizations are saying that the crowd may be bigger than ever.

Trump's influence

Trump has shared his support for the march, and Vice President Mike Pence will be there to give a speech on Friday – a pretty big deal considering March for Life says a Vice President or President has never spoken at the event before.

The election of President Donald Trump and a dominant Republican Congress have renewed optimism for Americans who are against abortion, according to CNN.

There are a few reasons for that.

For one, Trump indicated throughout his campaign that he would be putting forward an anti-abortion nominee to fill the vacancy on the Supreme Court – specifically someone wanting to change the Roe v. Wade decision.

Vice President Pence is also well-known for his anti-abortion views.

And on his first day in office, Trump signed an executive action to reinstate the so-called "Mexico City Policy," which bans international non-governmental organizations that perform or promote abortions from receiving US government funding.

But the likelihood of the new administration overturning Roe vs. Wade may still be slim. FiveThirtyEight points out that Roe vs. Wade was effectively re-affirmed in a Supreme Court ruling last year, Whole Woman’s Health v. Hellerstedt, when the court struck down a series of restrictions placed on abortion providers in Texas.

Trump appointing one new justice to the court is unlikely to make a difference, FiveThirtyEight said.

And according to a Pew Research Center poll, most Americans (seven out of 10) don't want to see it happen.

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