David Diamond, who died one day before Carlo Maria Giulini at the age of eighty-nine, was the last faithful representative of the mid-century populist school in American music. I will write about this often fiercely eloquent composer in a future New Yorker; for now, here are links to an obituary by Richard Dyer and to my own 1992 review of Diamond's Eleventh Symphony, which proved to be his final effort in the form.
Update: Lisa Hirsch reminds me that Harold Shapero, composer of a classic mid-century American symphony, is alive and well; Diamond was not the last of the breed. And a reader points out that Robert Ward, composer of The Crucible, has always remained loyal to the populist style, and recently completed his Seventh Symphony.