Q. In unpublished scholarly works, which are of course double-spaced according to Chicago style, should block quotations be double-spaced also, or should (or can) they be single-spaced?
A. Chicago style for the preparation of a manuscript that will be published is to double-space everything, even notes and block quotations. This style was created in the days when copy editors needed space between the lines to hand mark typos and other corrections. (It’s not true that quotations never need editing, and notes often require heavy editing.) Even now that manuscripts are edited with tracked changes, the author reviewing the editing on a printout must have room to respond to queries and make her own corrections.