For a Broadway musical that has lasted thousands of performances, played three different theaters, gone through a head-spinning number of cast changes and is about to reach its 20-year anniversary, “Chicago” is in remarkably good shape.

Celebs of all sorts go in and out of the show regularly (recent examples include a former teen star, “real housewife” and Heisman Trophy winner), which lends it a sort of newsworthiness.

But the ongoing vitality of “Chicago” is primarily the product of its highly capable ensemble (who flawlessly execute Ann Reinking’s Fosse-style dance choreography) and orchestra (led by longtime music director Leslie Stifelman) and the brilliance of its Kander & Ebb score and dark book satirizing fundamental American institutions as shameless showbiz.

At present, “Chicago” is enjoying a historic first in having two Mexican-born actors leading the cast: “Jane the Virgin” star Jaime Camil (who makes for a dashing and easygoing Billy Flynn) and Bianca Marroquín (who has been the merry murderess Roxie Hart on and off for years).

They are well complimented by Amra Faye Wright’s striking Velma Kelly, Roz Ryan’s assured Mama Morton, R. Lowe’s stylized Mary Sunshine and Raymond Bokhour’s sympathetic Amos. Among the ensemble I noticed Chryssie Whitehead from the Broadway revival of “A Chorus Line.”

If the original 1975 production was overshadowed by “A Chorus Line,” this stripped-down revival took Broadway by storm when it premiered in 1996, on the heels of the O.J. Simpson trial. Today, one can’t help but sense its relevance to the tactics being exercised in the current presidential election.

As it happens, this week, an all-female production of “Chicago” from Japan is simultaneously playing in New York as part of the annual Lincoln Center Festival, which serves as a testament to the musical’s international appeal.

For those without the ability to get a ticket to “Chicago” on Broadway, a free concert version of the show will be presented on Aug. 31 in Central Park as part of the SummerStage series.