It was a demonstration the likes of which haven't been seen in 40 years — this weekend's national pro environmental statement called "Step It Up."
It's part of a growing number of teens and college students who are picking up the banner of global warming, and running with it.
At a high school in San Gabriel, Calif., kids are working on a solar electric boat. Their classmates are tweaking a hydrogen fuel project, building a new electric bike and converting vegetable oil into bio-diesel. All, by the way, during their week off from school.
"A lot of these people here, that's all they want to do is make a difference — change the world — and I think we can do it," student Amanda Martinez says.
Environmental consciousness has been building among young people for years. It's gaining momentum with a focus on global warming.
This month's Step It Up demonstration involved hundreds of thousands of Americans in more than 1,400 events across the nation — all to demand drastic cuts in the carbon emissions believed partially responsible for global warming.
"I really want my kids to have a good life and I don't want them living in a smog-filled world," one demonstrator says.
The event was planned by Internet savvy students at Middlebury College in Vermont, and rapidly went viral on the Web with such speed it surprised even the environmental writer who encouraged the students to launch the campaign.
"I think especially with young people, it's the understanding that this is going to be their lives for the next 50, 60, 70 years," author Bill McKibben says.
"We want to fight this fight and we want to win this struggle."
"College students, especially, have just reached a breaking point and have finally become motivated to do something about it," college student Daniel Kane says.
Not since the '60s have campuses coordinated such a national event — student activism like the issue (or the Earth) itself, appears to be warming up.