NPR's Robert Siegel interviews Joseph Horowitz, author of Classical Musical in America: A History of Its Rise and Fall (stream here). It starts with the story of how Dvorak's premiere of the New World Symphony was treated as a moment of ecstasy in New York while the Boston elite were outraged that native and African-American sources were treated as "emblematic" of the United States. There was also a discussion of the conductor Arthur Nikisch, complete with an example of an old, idiosyncratic performance of Beethoven's Fifth Symphony. Horowitz also made his argument that, unlike how European classical music was driven by an indigenous canon, American classical music is associated with the "culture of performance." Horowitz also points out, as have Alex Ross, Marja-Leena Rathje and Lisa Hirsch, how Finland shines as a beacon of classical music, including its own contemporary composers.
The last third included an assertion that John Adams' Naive and Sentimental Music was an example of what we should be hearing in the concert hall, and that disappointingly, it has only been performed by five conductors in the United States, including the composer himself. Horowitz offers that the leading American composers, Glass, Reich, and Adams are also performers, for what it's worth. FInally, he thinks we are at a "propitious" moment where American orchestras need to take note of Post-Classical music and interact with it.
From studying the index, the book seems more composer-focused than I thought, given its premise. It also has a website with, via Naxos, sixteen relevant and streamable selections of American-composed music as well as a page of representative performance examples.
This book may be more important than I first thought.