"Pages, pages, how many pages," the Oak Park teen mumbled. "652!" she shrieked with excitement, clutching the book with anticipation.
The countdown began at 60 seconds; the crowd became increasingly excited at 20 seconds and was downright frantic as the last 10 seconds ticked away before the midnight release of the long-anticipated book.
Similar scenes played out from London to New York, where fans have been looking forward to the release of the latest volume in the series, which has developed a devoted following.
With millions of presold copies, the book is one of the biggest releases in history.
And there is no question that booksellers coast-to-coast have been anticipating the latest installment in British author J.K. Rowling's fantasy series. For independent retailers, a Harry Potter release can mean the difference between a good year and a bad one.
"It does drive other book sales," said Becky Anderson Wilkins, owner of Anderson's Bookshops in Downers Grove and Naperville.
Wilkins said many independent booksellers saw sales dip in 2004 from 2003, when "Harry Potter and the Order of the Phoenix" was released.
"We've never had anything like it," she said of the popularity of the Potter books.
Scholastic Inc., the American publisher of "Harry Potter and the Half-Blood Prince," reports shipping 10.8 million copies, the largest book release in history.
The book and audio edition already sit atop amazon.com's list of most popular items. Fans had preordered nearly 700,000 copies by June and the online bookstore is planning to ship more than 800,000 prepurchased copies of the book.
The Chicago Public Library preordered nearly 1,000 copies to distribute among its nearly 80 branches.
According to Associated Press, about 200 fans camped out at the Borders Bookstore on State Street.
Nichols Library in Naperville purchased 373 hardcopy and audio versions of the book and remained open Friday for the late-night release of the tome.
"We're all excited that a book can cause so much excitement and enthusiasm. Whole families are coming out and enjoying this," said library spokeswoman Susan Greenwood. This is the first time the library has stayed open until midnight. In response to the mania, retailers from Mt. Prospect to Naperville organized daylong festivals to fan the Harry hysteria.
Randhurst Mall in Mt. Prospect offered Harry Potter raffles, live music, a "wizard prison" and a life-size game of chess Friday.
Dubbed "Spellbound," the event began at 10 a.m., and like most of the parties, it concluded at midnight, when eager fans were finally able to make their book purchases.
Jessenia Guzman, 20, of Chicago walked the mall during the day dressed as a student from Hogwarts--the school of wizardry that Harry attends. She doesn't usually see many people her age at Potter parties, but that had no bearing on her enthusiasm.