Jump on the bandwagon Informal

To join a popular activity, opinion, or trend, especially because it has already become widely accepted or successful.

It often carries a mildly critical edge, suggesting the person joined for the sake of popularity or safety rather than genuine, independent conviction.

“Bandwagon” originated in mid-19th-century America as the literal name for a wagon that carried a circus band, with P.T. Barnum referencing “the ’band wagon’” in his 1855 autobiography. Circus parades used these decorated wagons to draw crowds, and 19th-century American politicians borrowed the same tactic, hiring bands and wagons to attract attention during campaign events. The figurative sense of joining a winning side developed by the 1890s, and Theodore Roosevelt’s 1899 letters contain an early clear example of the metaphor already in political use: describing supporters who “tumbled over each other to get aboard the band wagon” once his victory looked assured — capturing the exact modern sense of joining a cause specifically because it already looks successful.

Everyone jumped on the bandwagon after the show became popular.

He only likes that band because he jumped on the bandwagon.

Companies jumped on the bandwagon once the trend took off.

A: “Why did they suddenly support the idea?” B: “They just jumped on the bandwagon.”