The first Bumbershoot – named for a British slang term for umbrella – cost about $25,000 to put on. This one? Nearly $4 million, if you count trade-outs.

It’s not clear how many folks turned out for the first festival – the event was free for the first 10 years and there were no ticket stubs to tally. But according to long-time fans, there were no crowds.

There will be this year. Organizers are hoping for 250,000 visitors during the four-day event.

“We’re making offerings to the weather gods right now,” said festival producer Sheila Hughes of Seattle’s One Reel, which puts on the show with the 74-acre Seattle Center, site of the 1962 World’s Fair.

The huge lineup – more than 75 headliners in music, art, literature, drama, film, comedy and dance on over two dozen stages, galleries and other venues – offers something for just about every one of those hoped-for attendees.

“That’s the thing – when you have this many performances, you can really mix it up,” Hughes said.

“Last time we counted, we had about 2,500 artists coming in: film makers, poets, all the band members, visual artists, actors, dance – it’s the convergence!”

There’s a whole lot going on. But music drives the show, fills the air and makes the earth rumble underfoot. And there’s a huge selection:

Jonathan Richman, Southern Culture On The Skids, and Zap Mama are among the leading acts September 1, opening day.

The lineup expands Saturday. Featured acts include Tracy Chapman, George Clinton and Parliament/Funkadelic, Savage Garden, Vic Chesnutt, Karl Denson’s Tiny Universe, Mighty Clouds of Joy, and Elliott Smith.

A highlight of Sunday’s schedule is the pairing of Sleater-Kinney and Ronnie Spector at the Key Arena. But there’s plenty of other name acts at Bumbershoot that day – including Ani DiFranco, Indigenous, Maceo Parker, The Posies, Robbie Fulks, Kelly Joe Phelps, and Compay Segundo of Buena Vista Social Club.

Things wind down only figuratively on the fourth and final day of the fest, with Ben Harper, Joan Jett & the Blackhearts, Joan Osborne, Jimmie Dale Gilmore, Kristin Hersh, and Marc Ribot Y Los Cubanos leading the pack of performances on Monday.

RealNetworks will provide live and on-demand Web broadcasts of top musicians playing Bumbershoot’s six stages, including Motorhead, Jeffrey Gaines, Ozomatli and Modest Mouse.