WASHINGTON - Looking for an excuse to avoid celebrating Earth Day?

"There's nothing going on" is probably not going to fly. The Roots, Ricky Skaggs, Los Lonely Boys, the Neville Brothers and Mickey Hart from the Grateful Dead are among the headliners for eight simultaneous Earth Day festivals planned at major cities around the United States on April 20.

Organizers say the free events will be staged at parks in New York, Chicago, Dallas, Denver, Los Angeles, Miami and San Francisco.

The flagship event will be the Earth Day 2008 celebration on the National Mall in Washington.

Organizers hope to get more people talking about global warming.

Producer Peter Shapiro says "the issue of the environment hopefully crosses party lines."

"Our goal with this event is to make Earth Day more prominent," he said.

The events are being billed as the largest Earth Day celebration ever held in the United States.

Producers of the Green Apple Festival, which began three years ago in New York, and the Earth Day Network, a nonprofit created by the founders of the original Earth Day in 1970, are putting on the shows.

The Roots will headline the Washington event with the U.S. Capitol as their backdrop, along with political leaders, various speakers and other musical acts.

Speakers will range from Richard Cizik, vice-president of the National Association of Evangelicals, to Rev. Jesse Jackson, members of Congress and possibly some presidential candidates, said Kathleen Rogers, president of Earth Day Network. They're still trying to book Al Gore.

In New York, country singer Ricky Skaggs will perform in Central Park, and the Latin group Menudo will take the stage in Miami with hip-hop group Arrested Development. Los Lonely Boys will be the headline act in Dallas while the Neville Brothers take their funk and R&B act to Denver. Mickey Hart is expected to perform at Golden Gate Park in San Francisco.