Nothing's hotter than Harry Potter.

Even the character's creator, British author J.K. Rowling, can't answer why everyone is bewitched by the best-selling, multivolume saga about an orphan who discovers on his 11th birthday he's a famous wizard.

"I started writing these books for me. I never expected this in my wildest dreams," the 34-year-old former teacher said in the midst of her U.S. tour, which arrives in Chicago today. "What emerges from what children tell me is that they identify with one of the three main characters: Harry, Ron or Hermione."

The three Potter books - part of a projected series of seven - are stacked up at the top of the New York Times best-seller list where the first, Harry Potter and the Sorcerer's Stone, has been for more than 40 weeks. At last count, 8.2 million copies of the books were in print in America alone.

Since the first of three Potter books was released in America in August 1998, rampant Pottermania has been bubbling like a witch's cauldron. It will be at full boil when the author returns to Chicago for two days of book signings.

Still trying to catch their breaths, booksellers and childhood experts are beginning to try to explain the phenomenon.

"The supersonic (sales) boom occurred about two months ago and has something to do with children going back to school," said Richard Howorth, president of the 3,200-member American Booksellers Association. Howorth, who owns Square Books in Oxford, Miss., said, "Apparently, every child between the third and seventh grade in America is reading this book along with their moms and dads. Even adults without children are reading it."

A tremendous word-of-mouth is behind the surge, said a spokeswoman for Scholastic Publishing, which introduced the American edition of Harry Potter and the Sorcerer's Stone in 1998, a year after the original was published in England.

Gillian McNamee, an early childhood expert at the Erickson Institute in Chicago, whose own 10-year-old reads Harry, noted that children can easily relate to the books. "Kids are starved for play in a magical place," she said. "As they move into their middle years, they haven't lost the love to pretend."

"It's the story. Harry is somebody you can admire, who does remarkably well, given his circumstance," said Rose Joseph, co-owner of the Magic Tree bookstore, 141 N. Oak Park Ave., Oak Park. "Kids realize it's not real, but they love his overcoming adversity. And the author is wonderfully imaginative."

It's not likely that Pottermania will wane any time soon - especially with so many primed for the next installment's arrival in the summer of 2000: Top Hollywood filmmakers, including Steven Spielberg, are reported interested in directing a Potter film for the summer of 2001. Potter theme parties are popping up like mushrooms, and both children and adults are buying Halloween costumes to look like the tangle-haired, eye-glass-wearing Harry, who sports a lightning bolt on his forehead. Rowling's whirlwind, three-week U.S. tour, which began with an appearance on "The Rosie O'Donnell Show" last week, is reaching a level of hysteria rarely found in publishing. The Manhattan bookstore where she shared a billing 18 months ago with another author had to issue vouchers for about 1,000, who waited as much as five hours for a chance for Rowling to autograph a book. Signed first editions fetch $500 apiece. And there's the Dark Side of controversy. A local committee for the Richland County School Dist. 1 in Columbia, S.C., has begun reviewing the books at one of its 50 schools following a complaint from a half- dozen parents concerned about references to the occult and violence in the books.

While a handful of parents have voiced concerns, public religion expert Martin Marty dismissed the outcry as misguided.

"There are a series of Christian computer games coming out which exaggerate the biblical concept of spiritual war," Marty said. "It seems funny that you would gravitate to the biblical equivalent of witches, then attack the mild wizards in Harry Potter."

Rowling, aware of the protest, said she couldn't answer the questions about the book's religious content until the conclusion of book seven.

She said she understood a parent's rights, but said she had a problem if "they try to stop other people's children from choosing what they want to read."