An estimated 15,000 people braved the hot weather and crowded streets of downtown to support environmentalism, medicine and other scientific research as well as concerns over the Trump administration's stance on science.
Maguylo said she hopes people took what they learned Saturday and were inspired to tell government representatives to not make cuts to science programs.
While the events were non-partisan according to organizers, many marchers were in effect protesting Trump's proposal to sharply cut federal science and research budgets and his administration's skepticism about climate change and the need to slow global warming.
Organizers portrayed the march as political but not partisan, promoting the understanding of science as well as defending it from various attacks, including proposed USA government budget cuts under Trump, such as a 20 percent slice of the National Institute of Health.
There are cancer survivors and doctors with signs that say "science saves lives", she said, and estimated that 90 percent of the signs are not political.
Future scientists and their families had a chance to do hands on experiments at the field museum after the march. Trump has also scrapped information on methane emissions, removed the word "science" from the EPA's Office of Science and Technology mission statement, and rolled back standards on vehicle pollution.
The "March for Science" festivities included "teach-ins" on the National Mall and parades in midtown Manhattan and hundreds of other cities and towns.
In a statement, Trump said "rigorous science" goes into his administration's decision making. My sign says, without data, you're just another person with an opinion.
It's Earth Day, which means that, like every Saturday, there are widespread protests planned, only this time they're on behalf of science, rather than taxes or women, both odious to our president as well.
There was also a science fair feel, where lectures were given in tents and hands-on science tables for kids.
"Today, we have a great many lawmakers, not just here but around the world, deliberately ignoring and actively suppressing science", Nye asserted.
"Protecting the government's investment in science, particularly when that includes funding for public engagement, is incredibly important", she said.
In London, physicists, astronomers, biologists and celebrities gathered for a march past the city's most celebrated research institutions. "We want people who march for science to make sure their leaders know why".
"I think [people] have to speak up".
The sign showed the periodic table of chemical elements and said: "You're out of your element Donny (Trump)".
Organisers have a view that it can be challenging for scientists to communicate with the public and are even encouraging scientists to become politicians so that their voices can be effectively heard.
Nashville Predators Win Game 3 In Series Against St. Louis Blues
NOTES: After game three, the Ducks headed to Kelowna, British Columbia, for a two-day mini retreat ahead of Wednesday's game four. The Predators have won seven straight home playoff games dating back to last season, including the first three this postseason.
Scores game-winner in Game 2
That one found the net, as Steen deflected Alex Pietrangelo's wrister from the point at 12:59 for his third playoff tally. The Predators never got the man advantage in Game 2, and they got their first almost midway through the first period.