For more than a decade, Earth Day didn't happen in Columbus. Well, technically it did - it was just hard to find.

For more than a decade, Earth Day didn't happen in Columbus.

Well, technically it did - it was just hard to find.

You could've stumbled upon a few nonprofits and neighborhood groups gathering trash or planting trees. But from roughly 1994 to 2006, the city went without a large-scale event for the international environmental holiday.

Then, almost out of nowhere, Green Columbus changed everything.

What started in 2007 as the group's attempt to get 500 people to work four hours each has blossomed into the largest coordinated Earth Day volunteer effort in the country.

If you weren't able to help out last weekend, you can celebrate local green gains Saturday, April 23, at Franklin Park Conservatory during a daylong festival of art, music and eco-friendliness.

As Green Columbus events always do, Earth Day 2011: Lighten Up ends with a party.

"We do not have the largest Earth Day celebration in the world," said Erin Chacey, director of Green Columbus and this year's event. "It's the community-service projects that we are doing at a level that no one else in the country - and possibly the world - is doing."

About a billion people in 192 countries will commemorate the holiday founded in 1970 and observed officially on April 22, and some cities will draw bigger crowds than Columbus to eco-friendly festivals.

But no group in America coordinates a bigger number of work sites or volunteers.

"Green Columbus has done a really good job with volunteers," said Franklin Russell, a coordinator with the Earth Day Network, which organizes events around the globe. "Other cities are asking how to organize volunteer events, and Columbus is in that discussion."

More than 1,400 people worked a total of 3,900 hours during the first Green Columbus event, nearly double the original goal. By 2009, the number of participants jumped to 3,679.

Last weekend, 137 work sites spread from Big Darby Creek to Bexley, Delaware to Groveport. About 3,370 young, old and in between yanked invasive species, picked up litter, planted trees, prepared community gardens and built butterfly habitats.

And it hailed on Saturday.

"Everyone I've worked with has been so excited about the event and working together," said Cameron Goodyear of Clintonville, who helped organize two work sites this year. "People feel empowered to contribute - which you don't find a lot in our culture these days."

So how did a nonprofit group convince a city with no formal celebration that Earth Day is awesome?

At first, it simply connected the dots.

"We're really good at partnering," said Tad Dritz, Green Columbus' former director. "There were pockets of environmentalism all over the place that we tapped into with Earth Day. They were community-sized events, rather than citywide."

Smaller operations, fueled by growing buy-local and go-green movements, became part of the group's user-friendly Earth Day database, where site leaders could advertise projects and locals could pick the one that fit.

"We're about streamlining environmental practices - and that only happens when people are talking to each other and working together," Chacey said.

While connecting efforts around Central Ohio, Green Columbus began to attract many not involved previously with eco-friendly initiatives. The group's message was upbeat. Annual themes insisted that small changes matter - and that everybody could make a difference.

This year's premise, "Lighten Up," refers to reducing your carbon footprint, but it also pokes fun at environmentalism's familiar doom-and-gloom approach. The goal is to blur the boundaries that often keep activist and everyday person from joining forces.

"For example, hunters and environmentalists, they watch birds," Chacey said. "The point is, they both want the birds to be there. That's what people should be focusing on."

And, to bring people together, the group threw a party.

"No one was doing a large-scale volunteer effort and a party," Dritz said. "Now we call it a Columbus-style Earth Day event. People [in other cities] were kind of doing one or the other."

During the first several years, volunteers worked in the morning, washed their hands and hit Goodale Park for an afternoon of entertainment. Eventually organizers gave the party its own day, and the event blossomed alongside volunteer efforts.

This year's celebration will feature music, live art hosted by ARTillery and booths manned by both artists and environmentalists. It's open to all, though volunteers will receive a few freebies, like a scoop of Jeni's ice cream or a beer from Columbus Brewing Company.

"We're having such success with volunteers because people in Columbus are paying attention to what's going on in the world," Chacey explained. "And if you're paying attention to what's going on, then you're going to want to take some sort of action."