For the first time in its 14-year history, Capitol Hill Block Party will feature a third day in what's traditionally been a two-day music festival. This year it will run Friday to Sunday, July 23-25. Tickets go on sale Friday, May 21.

For the first time in its 14-year history, Capitol Hill Block Party will feature a third day in what’s traditionally been a two-day music festival. This year it will run Friday to Sunday, July 23-25.

Word from city officials and festival organizers is the Sunday addition is necessary to accommodate a major headliner available only that day, though the name of that headliner — and the rest of the Block Party lineup — has yet to be announced.

The third day was added after a request from festival organizers to the city was boosted by a groundswell of community support, which came via neighborhood and online petition and e-mails to city officials.

Headliner rumors have been zipping around the blogosphere; even money is on heavy rockers the Dead Weather, Jack White’s current project. As reported on the Capitol Hill Seattle blog, organizers expect the added day to bring in an extra 5,000 to 6,000 fans. The festival will feature more than 60 national and local bands — mostly indie rock, hip-hop, and electronic — on several indoor and outdoor stages.

The Block Party lineup will be announced Wednesday, June 2. Tickets go on sale May 21 via www.thestranger.com and will cost $23 per day or $60 for a three-day pass.

Jonathan Zwickel: 206-464-3239 or jzwickel@seattletimes.com