It started as a challenge. Author Diane Johnson, who divides her time between San Francisco and Paris, was having dinner in Provence with several French friends when one of them remarked that Americans were indifferent to their own history.

Johnson's friend went on to say that most Americans know little even about their own ancestors. "After they mention the Pilgrims or covered wagons, they fall silent; they know nothing," the woman sniffed.

Today, Johnson laughs about the incident. At the time, though, she was taken aback. The author, who was born and raised in the small Illinois town of Moline, realized that she knew little about her own family history. She decided to find out more.

The result is "Flyover Lives," a far-ranging memoir that combines Johnson's life story with those of her early American ancestors. Titled for the Midwestern zone that many coast dwellers regard as a no-man's land, the book traces her ancestors back to the early 18th century.

Johnson, a petite, vivacious woman whose previous books include the novels "Le Divorce" and "Le Mariage," says she was lucky -- much of the information she was seeking was available in a cache of documents preserved by an aunt.

"I knew that I had access to these documents, the diaries of my great-great-grandmother and my great-great-great-grandmother," she explains. "I knew that there was a little trove of letters. I knew those documents were there, and yet I had never been interested in sitting down and deciphering them. And I was hesitant about whether it would be interesting to other people." Reading those documents, she quickly changed her mind. Her forebears began arriving from France in 1711, becoming embroiled in wars and land acquisition schemes. The women's voices tell another story, and the book incorporates the writings of Johnson's great-great-grandmother, Catharine Martin, who endured enormous hardship on the Ohio and Illinois frontiers.

Married to a doctor who was often away, Catharine recorded life in a tiny hut, where hunger, disease and loneliness were constant companions. All three of her daughters died of scarlet fever.

"It was unbelievable," says Johnson. "We just don't realize what they had to do to survive. And these were middle-class women who had, for their day, good educations and professional husbands."

In contrast, Johnson was surprised by how much she enjoyed revisiting her hometown -- a place she'd always thought of as a "boring little river town where nothing ever happened." When she returned, towns like Moline and Chenoa, where Johnson's mother grew up, seemed idyllic.

"They were so sweet, and kind of unspoiled," she says. "For me, it was a real nostalgia trip. Moline was so pretty. I hadn't remembered that at all."

Johnson describes her childhood as largely uneventful. She loved to read and started writing at a young age. While still in high school, a teacher encouraged her to enter a contest to become a guest editor at Mademoiselle magazine. "Flyover Lives" recounts her first visit to New York and her immersion in the world of publishing.

Since then, she's traveled widely and published fiction and nonfiction. She did some writing for television, which led to screenwriting; the book recounts her work with directors Mike Nichols and Stanley Kubrick. She wrote the screenplay for Kubrick's "The Shining" at the director's English country home and calls him a great collaborator. "I'd never written a screenplay until then," she says. "He said, 'Great, that's what I want. I don't want anybody whose ideas have been blighted by trashy manuals or previous directors.' We talked over every detail -- he had a very literary approach to the script. I really learned from him."

Today, Johnson and her husband, John, a retired UC San Francisco professor who works for the International Union Against Tuberculosis and Lung Disease, maintain residences in Paris (on the Rue Bonaparte) and San Francisco (a house in Russian Hill). Johnson has definite ideas about both cultures -- she adores Paris, especially the ease of the city's train system (she doesn't drive) but still calls San Francisco home. "The fact that everything's in English is a great plus for me," she says, smiling.

"Flyover Lives" is her 16th book, but Johnson is already plotting a new one. It's a novel about an American woman who returns home after an extended period of living in Paris. "It's kind of a Jamesian subject," she allows. "I hope to profit from the sort of vision, the clarity you have when you first return to a place, before everything seems normal again."