Is Washington the new New York? Black the new grey? T.I. the new Snoop Dogg?

Who knows. But at The Washington Post, Mumbai is the new Bombay, Chennai is the new Madras and Kolkata is the new Calcutta.

From an internal announcement:

Effective Monday, Sept. 4, for editions of Tuesday, Sept. 5, we are
joining most other major news organizations and the National GeographicAtlas (our standard for place names) in referring to three Indian cities by their official names:

Bombay becomes Mumbai
Madras is Chennai
Calcutta is Kolkata

For the next several months, when writing about any of these cities, please include a clause after the first reference to read something like "Mumbai, formerly known as Bombay," or just "formerly Bombay."