Citation Trivia Question:

There are many federal courts for C___ (e.g., for the Central District of California), some for D___ (e.g., for the District of Wyoming), and at least one for A___ (the Armed Forces). But to my knowledge, there has been only one for B___. Which is it? The answer is below.

(Show.)

UPDATE: Tense and state corrections made, with thanks to commenter (and former summer-camp-mate of mine) Ira Matetsky and to the infallible Pius XXX.