Abortion opponents are gathering in Washington for the “March for Life,” an annual rally to mark the anniversary of Roe v. Wade, the Supreme Court decision that legalized abortion in 1973.

View Photo Gallery: The Catholic Church in particular is credited with organizing and driving the anti-abortion movement for decades, but religious arguments shape the pro-choice side, too.

“Though abortion might be legal, not every American supports this travesty of justice,” marcher Danielle Bean wrote in The Post on Sunday.

The rally begins at noon on the Mall, and House Speaker John Boehner (R-Ohio) is scheduled to address the marchers. Get traffic updates from Dr. Gridlock here.

Read more and follow along with The Post’s Katherine Driessen, who is tweeting from the march, after the jump:

With an election looming and access to contraception and abortion services hanging in the balance, antiabortion and abortion rights activists are preparing for battle over the course of 2012. Saturday was the 39th anniversary of the Roe v. Wade ruling, a day after the Obama administration announced that most church-affiliated organizations would be required to offer workers birth control coverage. In early January, 25 Kansas House members agreed to sponsor a “personhood amendment” to ban abortion, a measure similar to the one Mississippi voters rejected last November.

“Right now, there are 19 state governments that are solidly anti-choice, meaning that the legislatures and governors oppose abortion rights,” NARAL Pro-Choice America President Nancy Keenan told The Post’s Sarah Kliff. “There are 44 mixed-choice states. Between all of them, there’s a lot of space for things to get even worse.”

This battle will be an issue in this year’s presidential race. Here’s where each of the GOP candidates stand, according to the Associated Press:

Gingrich: Platform calls for conservative judges and no subsidies for abortion but not a constitutional abortion ban.

Paul: Says federal government should have no authority either to legalize or ban abortion.

Romney: Says Roe v. Wade should be reversed by a future Supreme Court and states should decide their own abortion laws.

Santorum: Favors constitutional abortion ban and opposes abortion even in cases of rape.

Live tweets: