Richard Powers' "The Echo Maker," a scientific tale of memory and identity in the age of Sept. 11 and the Iraq war, won the National Book Award for fiction Wednesday night, honoring a widely respected author with a small but passionate readership.

Timothy Egan's Dust Bowl history, "The Worst Hard Time" won for nonfiction; Nathaniel Mackey's musical and mystical "Splay Anthem" took the poetry prize; and M.T. Anderson's "The Astonishing Life of Octavian Nothing, Traitor to the Nation, Vol. I," a multi-formatted epic in 18th century prose, was cited for young people's literature.

Winners each receive $10,000, runners-up $1,000.

Powers, 49, has long worked in his love for science in such works as "Galatea 2.2" and "Operation Wandering Soul."

"The Echo Maker" includes passages on neurology and clinical psychology in a story about a man who loses his memory in a car crash and the sister who agonizes over his failure to recognize her. Powers' award also continues a long tradition of literary prizes for publisher Farrar, Straus & Giroux, which in recent years has won numerous Pulitzers and National Book Awards with such works as Jonathan Franzen's "The Corrections" and Marilynne Robinson's "Gilead."

"I am deeply indebted to FSG for encouraging me to work in total freedom for the last 12 years, writing books that have not always been easy to market or classify," Powers said in his acceptance speech.

Anderson, the young people's literature winner, also cited the indulgence of his publisher, Candlewick Press. He thanked Candlewick for taking on a long and unusual book by a "neurotic who rarely leaves his house or gets dressed."

Powers' book refers often to the news of the time, setting his narrative against the shock of the terrorist attacks and the determined path to the Iraq war. Two fiction finalists were equally topical; Jess Walters' "The Zero" and Ken Kalfus' "A Disorder Peculiar to the Country" were both set directly after Sept. 11, 2001. The other nominees were Mark Z. Danielewski's free verse, time traveling "Only Revolutions" and Dana Spiotta's "Eat the Document," a story of 1970s radicals hiding their past.

Memory, and the increasingly distant past, was a theme in the acceptance speech of Egan, who recalled interviewing Dust Bowl survivors, many in their 80s and 90s.

"We are a storytelling nation. We need to inhabit a narrative as a nation," said Egan.

Other nonfiction nominees were Taylor Branch's "At Canaan's Edge," the last of his celebrated civil rights trilogy; Rajiv Chandrasekaran's Iraq war report, "Imperial Life in the Emerald City"; Peter Hessler's "Oracle Bones: A Journey Between China's Past and Present"; and Lawrence Wright's best-selling Sept. 11 investigation, "The Looming Tower."

Poetry finalists besides Mackey were "Averno," by former U.S. poet laureate Louise Glueck; H.L. Hix's "Chromatic"; Ben Lerner's "Angle of Yaw"; and James McMichael's "Capacity."

Like the fiction category, the young people's nomination features a variety of styles, including Anderson's "Octavian Nothing"; Gene Luen Yang's "American Born Chinese," the first graphic novel to receive a National Book Award nomination; and Patricia McCormick's "Sold," another story told in free verse. The other finalists were Martine Leavitt's "Keturah and Lord Death" and Nancy Werlin's "The Rules of Survival."

The National Book Foundation is a nonprofit organization that sponsors numerous readings and educational programs.