For adults without children, she is mostly unknown. But among parents and children between 5 and 9, she has achieved an almost cult-like following whose popularity rivals J.K. Rowling.

Last Thursday evening, more than 1,000 of her fans crowded into Quail Ridge Books & Music in Raleigh to see Mary Pope Osborne, author of the bestselling Magic Tree House books. The series follows the journeys of a brother and sister, Jack and Annie, as they are transported back in time and experience adventure filled with “history, mystery and magic.”

Past titles include Dolphins at Daybreak, Mummies in the Morning, Twister on Tuesday and Summer of the Sea Serpent.

Osborne was here to promote her 35th book in the series, Night of the New Magicians. She was accompanied by her sister, Natalie Pope Boyce, who writes the research guides for the books. The series has sold almost 40 million copies and has been translated into 26 languages. For the past several weeks, it has been No. 1 on The New York Times bestseller list for children’s series books, edging out Harry Potter.

The atmosphere Thursday night was electric. Kids, parents and teachers, books tucked under their arms, weaved their way between aisles of books and outside the store. Many children sprawled on the carpet quietly reading the latest book and waiting for their number to be called to get in line. Others giggled in excitement as they moved closer to the two authors seated in the back of the store signing books.

Osborne wore a wrist brace, the result of signing almost 3,000 books the night before in Philadelphia. She apologized to the crowd in Raleigh that she could only sign two books per child. At each appearance she gives a short presentation and asks the audience for book suggestions. Osborne explained that her best ideas come from kids.

The children eagerly gave their opinions on ideas for future books. A few years ago at a bookstore in California, Osborne mentioned the title of her newest work in progress, Holiday in Hawaii. A second grader yelled out, “I have a better title. Why don’t you call it High Tide in Hawaii?” Osborne agreed. High Tide in Hawaii became a New York Times No. 1 bestseller.

Osborne and her husband, Will, live in western Connecticut. Both are 1971 graduates of UNC-Chapel Hill. Will is an actor and playwright and wrote the Morehead Planetarium show Magic Tree House Space Mission. It is the most popular show at the planetarium. He also wrote many of the research guides. He is now writing a musical for the stage about Jack and Annie.

Osborne has refused movie and television offers for the series, maintaining she wants children to read and use their imaginations. According to many teachers, the series works wonders in instilling a love for reading.

At every signing Osborne hears parents and teachers, some almost in tears, explain how the books changed their child’s life. “He never read before and now he can’t stop reading,” one father said at Quail Ridge. Many children told Mary and Natalie how grateful they were for the books. Some proudly presented letters, photographs and drawings. A child ended one letter with: “You keep writing and I’ll keep reading.”

After waiting almost three hours, a youngster announced to everyone that he had read the 112-page Night of the New Magicians while in line. Some of the students said they had formed their own Magic Tree House reading clubs. A second-grader told Osborne that he and his friends have come up with a title for a new work, a bit of history they would like to see in an upcoming book: Hippies on Holiday.

After leaving Raleigh, Osborne and her sister visited their mother in Greensboro and spent Saturday afternoon signing books at a Barnes & Noble store. Groups of students and parents came from as far away as Asheville and Charlotte. More than 1,500 fans showed up.