At the time of the March for Life's inception, pro-life attitudes were a bit more closely aligned with the Democratic party, and it wouldn't become a deeply divisive partisan issue for several more years. Some of the earliest featured speakers at the March for Life even included several now-prominent pro-choice advocates – Joe Biden, Jesse Jackson and Harry Reid, to name a few, Mancini said.
"The first year the March happened, it was very small and there were a lot of legislators," she said. "Now, it's much more cultural."
The movement grew because it had to.
Through the '70s and '80s, the national March remained a relatively small movement of politically minded activists. During the Reagan presidency, pro-life issues shifted from slightly left to more definitely right.
But it wasn't until the mid-1990s that the March became a much more youthful, grassroots and cultural event.
"Nellie Gray (the founder of the March for Life) was working very closely with churches and bishops, it was really grassroots and very Catholic, so more and more schools started bussing young people in for the march for life," Mancini said.
Now, the March for Life has a reputation for being a youthful event – hordes of college and high school students descend on Washington D.C. during the days leading up to the event, bringing lively chants and songs and colorful posters with them as they make their way to the capitol, often in freezing winter weather.
"You're not alone"
Aimee Murphy is one of those young people that started attending pro-life events at the age of 17. At the time she was a pro-life atheist, and often felt like the odd one out in her high school – but meeting other young people at bigger events like the March for Life made her realize that she wasn't alone.
"It was so important for me as a young person to see...that I was not the only high school student who cared about the pre-born," she told CNA.
Now a millennial activist and the Executive Director of the "Life Matters Journal," Murphy said it's easy, and maybe even fair, to criticize the March for Life as an expensive, superfluous event – if it remains just that.
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"If you don't go home and do something the March for Life is useless," she said.
"As pro-life activists who struggle against a culture and a media and a legislature who isn't willing to do anything that would actually make a difference in terms of abortion, you face this idea that the evil is too big, there's nothing that I personally can do, and you'll sit around and feel bad for yourself," Murphy said.
"But the March for Life, inasmuch as it gives people hope and encourages them to do something and change what is going on, then it's absolutely priceless."
That sense of community and solidarity, particularly with other like-minded young people, is crucial to keeping high school and college students engaged in the pro-life movement after they graduate said Kristan Hawkins, president of Students for Life of America.
Last year alone, there were around 200,000 people in attendance at the national March – many of them students and young adults.
"We tell everyone to at least come once, because it's a formative event," she said. "The key to making them life-long activists is getting people to understand that this is a group that they want to be a part of, and this is a group that's winning, and the March for Life does that."