When Leonard Bernstein was named music director of the New York Philharmonic in 1958, his appointment was hailed as a breakthrough for orchestra conductors from the United States.

For decades, American maestros had been cast aside in classical music, seen as inferior to Europeans. But Bernstein’s rise, recently glamorized in the Oscar-nominated “Maestro,” showed that conductors from the United States could compete with their finest counterparts across the Atlantic.

Commentators predicted a golden age for American conductors at the top American orchestras. Some followed in Bernstein’s footsteps — including protégés of his — and as recently as 2008, there were American music directors leading orchestras in Atlanta, Baltimore, Boston, New York, San Francisco, Seattle, St. Louis and Washington, D.C.

Today, the only one of those ensembles still led by an American is the Baltimore Symphony Orchestra. Four of the 25 largest ensembles in the United States have an American at the podium, and at the nation’s biggest, most prestigious orchestras, American music directors are entirely absent.

“It means that we’ve got a lot of work to do,” said Jonathon Heyward, who grew up in South Carolina and began serving as the Baltimore Symphony’s music director last fall. “We have to continuously think about ways to better relate to an American community.” (Heyward is one of those four American maestros at the largest ensembles today, along with Michael Stern in Kansas City, Giancarlo Guerrero in Nashville and Carl St.Clair at the Pacific Symphony in California.)

Classical music has long been a global industry. The Berlin Philharmonic is led by a Russian-born maestro, Kirill Petrenko; the Bavarian Radio Symphony Orchestra in Germany, by a British-born conductor, Simon Rattle. Just as maestros from overseas have assumed top conducting posts in the United States, American artists have gone to Europe, Asia and elsewhere to lead renowned ensembles. Alan Gilbert, the former music director of the New York Philharmonic, now has orchestras in Germany and Sweden.