People attend the anti-abortion March for Life rally on the National Mall in Washington on Friday.
CNN  — 

Crowds of people packed the National Mall on Friday for the March for Life, an annual march against abortion.

Citizens from all corners of the United States braved the frigid weather, chanted anti-abortion slogans, waved flags and hoisted signs as activists and lawmakers argued against the practice of abortion.

The event included a video message from President Donald Trump and an address by Vice President Mike Pence.

Trump listed his anti-abortion efforts, including the reinstating of the “Mexico City Policy,” which bans aid to groups that “support or promote abortion around the world,” and cited actions “to protect the religious freedoms of doctors, nurses and charities like the Little Sisters of the Poor.”

“I am supporting the US Senate’s effort to make permanent the Hyde Amendment, which prohibits taxpayer funding for abortion in spending bills. Today, I have signed a letter to Congress to make clear that if they send any legislation to my desk that weakens the protection of human life, I will issue a veto. And we have the support to uphold those vetoes,” he said.

Pence, who praised Trump as the “most pro-life president in American history” and whose remarks were greeted with applause, said the anti-abortion movement is making strides throughout society and said the gathering reflects the demonstrators’ belief in life, compassion and freedom for the “born and unborn.”

“Forty-six years ago this month the majority on the Supreme Court turned its back on that right, but in that moment, a movement was born, a movement defined by compassion and love; a movement animated by faith and truth; and a movement that’s been winning hearts and minds every day since,” Pence said.

The anti-abortion march is held in Washington and has taken place every year since 1974. Since the Supreme Court ruled abortion legal in 1973, marchers have descended upon Washington to protest the decision.

“The March for Life began in Washington, DC, as a small demonstration and rapidly grew to be the largest pro-life event in the world,” the march’s website reads.

This year’s theme is “Unique from Day One.” with an emphasis on the connections between science and the anti-abortion cause.

“Science is on the side of life,” the March for Life 2019 website said.

“When life begins and the stages of prenatal development are scientific facts. Humanity – and our uniqueness as individuals – begins at day one, at fertilization. Life, in its most vulnerable form, should be protected.

“That, in essence, is why we march. We march to end abortion, with the vision of a world where the beauty, dignity, and uniqueness of every human life are valued and protected.”