"This seems to me a very dramatic thing in a democratic society," he said.
While little-known to the general public, Mr. Carter was long respected by an inner circle of critics and musicians. In 2002, the New York Times said his string quartets were among "the most difficult music ever conceived," and hailed their "volatile emotions, delicacy, and even, in places, plucky humor."
He remained active, taking new commissions even as he celebrated his 100th birthday in December 2008 with a gala at Carnegie Hall. "I'm always proud of the ones I've just written," he said at the time.
In 2005, his Dialogues, which had premiered the previous year, was a finalist for the Pulitzer Prize in music. And in 2006, his Boston Concerto was nominated for a Grammy as best classical contemporary composition.
He won his first Pulitzer in 1960 for his String Quartet No. 2; his second was in 1973 for his String Quartet No. 3. When the first National Medal of Arts awards were given in 1985, Mr. Carter was one of the 10 honored. The New Grove Dictionary of American Music said that at its best, Carter's music "sustains an energy of invention that is unrivaled in contemporary composition."
Carter said he found Europeans more receptive to his work than Americans because music in Europe is not purely entertainment but part of the culture, "something that people make an effort to understand."
The lack of widespread attention didn't bother him. "I don't think it means anything to be popular," he said. "When we see the popular tastes and the popular opinion constantly being manipulated by all sorts of different ways, it seems to me popularity is a meaningless matter."
Besides composing, he wrote extensively about 20th-century music. The Writings of Elliott Carter: An American Composer Looks at Modern Music was published in 1977.
Mr. Carter was born in New York in 1908, studied literature at Harvard, and then studied music in Paris under Nadia Boulanger.
As he turned 100, he recalled hearing the 1924 New York premiere of Stravinsky's revolutionary Rite of Spring. "I thought it was the greatest thing I ever heard, and I wanted to do like that, too. Of course, half the audience walked out, which was even more pleasant to me. It seemed much more exciting than Beethoven and Brahms and the rest of them."
He is survived by a son and grandson.