Citation, Documentation of Sources

Q. I am citing a specific tweet according to the guidelines in CMOS 14.209. But if the tweet was published before July 2023, should I list the website as Twitter or X? Thanks!

A. Whether it’s a book from the 1970s or a post on social media, sources are generally cited as published. For books, that means recording the publisher’s name as listed on the title page, even if that name has changed or no longer exists. But when you cite an older tweet, the URL in the citation will direct readers to that same tweet (if it hasn’t been deleted) but on what is now called X (and whether the domain is or

To make the situation clear even for readers who may not be aware of the change, add “now X” in parentheses after “Twitter” in your source citation: “. . . Twitter (now X) . . .” A post published after the name change would be cited as having been published on X (no need to add “formerly Twitter”).