Styleguide Wednesday

Latent Print presents Styleguide Wednesday, a post each Wednesday featuring an editorial convention from the world of styleguides. Whether a book, a spiral-bound manual, a stack of stapled 8½ x 11s, or a work-in-progress project stylesheet, these guides are the conversation on which the work of editors and other publishing professionals is based. View previous Latent Print moments of stylebook study and reflection here. This week features capitalization of generic nouns in plural uses.

Chicago 8.57 inspires the following example: Bays Chesapeake and Delaware but the Chesapeake and Delaware bays. The entry tells us, “When the generic term comes second and applies to two or more names, it is usually lowercased.”
But, in the AP Stylebook, “Lowercase the common noun elements of names in all plural uses.”
Why the distinction? As always, Latent Print is open for your comments.