Q. Does CMOS have guidance for the White House’s recent changes to the names of the Gulf of Mexico and Denali?
A. Relative to matters of style, yes: Spell a generic word like gulf with an initial capital when it’s used as part of a proper name but not otherwise (“the Gulf of Mexico,” but “the gulf”; see CMOS 8.54); don’t add “Mount” before the name Denali (see 8.56); and spell out “Mount” in names like Mount McKinley rather than abbreviating it as “Mt.” (see 10.35).
Other than that, it’s easy enough to confirm that the names of those two geographic entities were officially changed (at least in the United States) to the Gulf of America and Mount McKinley, respectively, in accordance with an executive order issued on January 20, 2025, by the White House. What an author does with that information will then depend on various factors, including a publisher’s house style (if any) and considerations related to historical accuracy.
For additional guidance, see the AP Stylebook, which issues regular updates geared toward those who cover the news. In a pair of updates added on January 30, 2025, that guide says to use the original name for the gulf “while acknowledging the new name,” but, for the mountain, it says that “the Associated Press will use the new official name of Mount McKinley.” For the gulf, AP points to the long history of the older name together with the fact that the gulf shares its borders with Mexico; for the mountain, AP cites the fact that it lies entirely within the United States, which lends broader authority to that name change.