Critics were in doubt. They thought no group could draw a crowd as large surrounding such a "controversial" issue.
"Everybody said women wouldn't march for abortion rights," Feminist Majority President Eleanor Smeal, who helped organise and speak at the march, told The Independent. "We said, 'Oh yes they will'."
"We wanted to make sure that people understood the overwhelming popularity of this issue, and we wanted it to be big," she added.
The Feminist Majority was joined with six other feminist and civil rights organisations to organise and guide the march: National Organisation for Women (NOW), American Civil Liberties Union, Black Women's Health Imperative, NARAL Pro Choice America, National Latina Institute for Reproductive Health, and Planned Parenthood.
Toni Van Pelt, current NOW president and organiser of the March for Women's Lives on 25 April, 2004 explained to The Independent that the political environment helped spark the need for a protest.
"There was so much government interference and we had no government support for the terrorism that was going on in the (reproductive) clinics," she said. "We were marching for the right to abortion, birth control, and all reproductive options, including the right to have children and determine when we were going to have families.
"That was really important to us."
Final tallies from the march revealed an estimated 1.3m women, men, girls, and boys flooded Washington DC to protest the Bush administration and stand up for abortion rights - a number none of the organisers anticipated.
"We didn't know it was going to hit over a million. No one could've predicted that," Ms Smeal said. "But we thought we would break all standards, and we did."
The March for Women's Lives became the largest march Washington had ever seen. But then the 2017 Women's March, just one day after President Donald Trump was inaugurated, broke all records by boasting a crowd of an estimated 3.2m to 5.2m fighting for women's rights.
Making the 2004 march all the more exciting was the celebrities who also descended on Washington to support the movement. Stars like Susan Sarandon, Whoopi Goldberg, Ashley Judd, and Julianne Moore all attended.
Speaker after speaker appeared on one of two stages set up during the march to speak to the crowd about how imperative it was to advocate for women's reproductive rights.
"We are here to take back our country," American feminist and political activist Gloria Steinem shouted into the crowd.
Signs rooting for presumed Democratic candidate John Kerry were pictured during the march, showing who some activists supported. President George W Bush would later defeat Mr Kerry in the 2004 election.
Prominent Democratic leaders including House Speaker Nancy Pelosi and Senator Hillary Rodham Clinton were also in attendance.
"We didn't have to march for 12 long years because we had a government that respected the rights of women," Mrs Clinton said, according to The New York Times. "The only way we're going to be able to avoid having to march again and again and again is to elect John Kerry president."
What the senator didn't know then was that her words would hold more impact 16 years after the monumental march.
In 2020, America is once again in an election year with a Republican president vying for a second term, all while putting judges in place who vowed to dismantle reproductive and abortion rights across the country.
Now more than ever laws like Roe v Wade were at risk despite the pro-choice movement growing in force within the last 16 years.
"They're trying, they're trying," Ms Smeal said about the Republican opposition. "They're trying to stack the courts and they are stacking the courts. Not just the Supreme Court, but the lower courts."
"It's very unpopular. The backlash will be severe," she added.
About 57 per cent of Americans label themselves as "pro-choice", a number that has grown since 2004, compared to 35 per cent who define themselves as "pro-life", according to a 2019 NPR/PBS NewsHour/Marist poll. When divided among parties, 74 per cent of Democrats, 60 per cent of Independents, and 29 per cent of Republicans consider themselves "pro-choice".
Despite the pro-choice movement winning the majority of American support, the opposition has pushed momentum towards decreasing access to abortion and reproductive services. And the coronavirus has only helped this movement with governors in Texas and Alabama, to name a few, attempting to block abortion services by listing them as non-essential, elective surgeries during the pandemic.
"They're driving people out that want to perform these services for these women," Ms Pelt said, adding the virus ban was "egregious" and "attacking all these different angles" when targeting clinics and their doctors.
The US Centre for Reproductive Rights issued an emergency lawsuit against five states during the pandemic to ensure clinics could perform their abortion services.
In Alabama, US district judge Myron Thompson issued a preliminary injunction on Sunday to prevent the state from forbidding abortions as part of the elective medical procedures ban during Covid-19. The decision would now be up to individual clinics on if they want to halt performing the procedure.
While the ruling was a victory for abortion-rights activists, the fight remains in other states like Texas and Ohio.
Another fight in Alabama could land on the doorsteps of the US Supreme Court and put 1973 Roe v Wade at risk, one of the most landmark court rulings that protects a pregnant woman's right to an abortion without excessive government restrictions.
Alabama passed a law in 2019 that was almost a near-total ban on abortions in the state and was expected to go into effect in November before a federal judge blocked it. Judge Myron H. Thompson wrote the law violated the Supreme Court's ruling and "defies" the constitution. But activists expected the opposition to push back.
"We think that this case will go to the Supreme Court," Ms Pelt warned. "This might be the one to try to overturn Roe v Wade."
People could argue another March for Women's Lives might be needed more than ever 16 years after the last one, as the right to abortion nears what would be another monumental Supreme Court decision.
"A lot of Women's March events that got to be really massive and public took place at moments like this one, where everyone expected the Supreme Court to roll back abortion rights," Mary Ziegler, legal historian and author of Abortion and The Law in America, told The Independent.
"It's been a way of bringing people into the Women's March and probably into the women's movement, because of the unique visibility of the abortion issue," she added.
Despite the fight from the pro-life movement, the political and social landscape for America has greatly changed since the last March for Women's lives.
"In 2004, not only was Bush in, but we were having trouble with both parties," Ms Smeal said. "Now it's 2020 and we have the nominee for the Democratic Party pro-choice. We just have to do something with the other party."
"You never hear anybody saying, 'The women's vote is not affected by the abortion vote.' Everybody knows that it is very, very strongly held," she added.
Medical abortions, which occurs when pills are used to aid an abortion, and over-the-counter emergency contraception without prescriptions are also now additions to women's reproductive services.
But the "fight", as Ms Smeal put it, still goes on for the movement. "We'll win," she said.
In case the movement experienced legislative setbacks, though, activist organisations were prepared to provide access to abortion services for all women that were safe, legally or not.
"We're preparing right now to make sure that women have access to abortion, whether they change the law," she said. "It really doesn't matter what the law is. As long as women can get pregnant there will be abortions. We need to make it safe, legal, accessible, and affordable for women."
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies